Ophthalmic information processing apparatus, ophthalmic apparatus, ophthalmic information processing method, and recording medium

ABSTRACT

An ophthalmic information processing apparatus includes a specifying unit and an image deforming unit. The specifying unit is configured to specify a three-dimensional position of each pixel in a two-dimensional front image depicting a predetermined site of a subject&#39;s eye, based on OCT data obtained by performing optical coherence tomography on the predetermined site. The image deforming unit is configured to deform the two-dimensional front image, by changing position of at least one pixel in the two-dimensional front image based on the three-dimensional position, to generate a three-dimensional front image.

TECHNICAL FIELD

The present invention relates to an ophthalmic information processingapparatus, an ophthalmic apparatus, an ophthalmic information processingmethod, and a program.

BACKGROUND ART

In recent years, attention has been drawn to optical coherencetomography (OCT) which is used to form images representing the surfacemorphology or the internal morphology of an object to be measured usinglight beam emitted from a laser light source or the like. Since OCT doesnot have invasiveness to human body as X-ray CT (Computed Tomography)does, development of application of OCT in medical field and biologyfield is particularly expected. For example, in the ophthalmic field,apparatuses for forming images of the fundus, the cornea, or the likehave been in practical use. Such an apparatus using OCT imaging (OCTapparatus) can be used to observe a variety of sites of a subject's eye.In addition, the OCT apparatuses are applied to the diagnosis of variouseye diseases.

Doctors or the like diagnose the state of the subject's eye by observingcolor front images, tomographic images, or three-dimensional images ofthe subject's eye acquired by performing OCT. Specifically, the doctorsor the like determine the morphology of the fundus from the color of acolor two-dimensional fundus image, or the morphology of the fundus froma tomographic image or a three-dimensional image.

For example, Patent Document 1 discloses a method of displaying both ofthe front image and the tomographic image of the fundus side by side.Further, for example, Patent Document 2 discloses a method ofstereoscopically observing the front image of the subject's eye, inorder to facilitate the diagnosis of diseases to be graspedstereoscopically, such as posterior staphyloma.

PRIOR ART DOCUMENTS Patent Documents

[Patent Document 1] Japanese Unexamined Patent Publication No.2008-154704 [Patent Document 2] Japanese Unexamined Patent PublicationNo. 2018-075229

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, in the method disclosed in Patent Document 2, the front imageof the fundus is changed into the stereoscopic image based on the shapeinformation of the predetermined layer boundary in the retinal layer,and the front image that has been changed into the stereoscopic image issuperimposed on the three-dimensional OCT image to generate a stickimage. To generate the stick image, the position matching between thefront image and the two-dimensional front image generated from thethree-dimensional OCT image is performed. Thus, the processing forstereoscopically observing the front image of the subject's eye becomescomplicated, and a method for stereoscopically observing the front imageof the subject's eye with a simpler process is desired.

The present invention has been made in view of such circumstances, andan object of the present invention is to provide a new technique forstereoscopically observing a front image of the subject's eye with asimple process.

Means of Solving the Problems

The first aspect of some embodiments is an ophthalmic informationprocessing apparatus, including a specifying unit configured to specifya three-dimensional position of each pixel in a two-dimensional frontimage depicting a predetermined site of a subject's eye, based on OCTdata obtained by performing optical coherence tomography on thepredetermined site, and an image deforming unit configured to deform thetwo-dimensional front image, by changing position of at least one pixelin the two-dimensional front image based on the three-dimensionalposition, to generate a three-dimensional front image.

In the second aspect of some embodiments, in the first aspect, thespecifying unit includes a site specifying unit configured to specifythe predetermined site based on the OCT data, and a pixel positionspecifying unit configured to specify the three-dimensional positioncorresponding to a pixel of the predetermined site in thetwo-dimensional front image, based on correspondence information inwhich positions of pixels of the two-dimensional front image areassociated with A-scan positions in the predetermined site in advance.

The third aspect of some embodiments, in the first aspect or the secondaspect, further includes a shape correcting unit configured to correct ashape of the predetermined site by correcting the three-dimensionalfront image so as to follow traveling directions of measurement light.

The fourth aspect of some embodiments, in the first aspect or the secondaspect, further includes a shape correcting unit configured to correct ashape of the predetermined site by correcting the OCT data so as tofollow traveling directions of measurement light, wherein the specifyingunit is configured to specify the three-dimensional position based ondata corrected by the shape correcting unit.

The fifth aspect of some embodiments, in any one of the first aspect tothe fourth aspect, further includes a designation unit used fordesignating a point of view in a predetermined three-dimensionalcoordinate system, a projection unit configured to project thethree-dimensional front image onto a two-dimensional plane in thethree-dimensional coordinate system in a line of sight direction passingthrough the point of view designated using the designation unit, and adisplay controller configured to display an image on a display unit, theimage being projected onto the two-dimensional plane by the projectionunit.

The sixth aspect of some embodiments, in any one of the first aspect tothe fifth aspect, the predetermined site is a fundus or vicinity of thefundus.

The seventh aspect of some embodiments is an ophthalmic apparatus,including an imaging unit configured to acquire the two-dimensionalfront image, an OCT unit configured to acquire the OCT data, and theophthalmic information processing apparatus of any one of the firstaspect to the sixth aspect.

The eighth aspect of some embodiments is an ophthalmic informationprocessing method, including a specifying step of specifying athree-dimensional position of each pixel in a two-dimensional frontimage depicting a predetermined site of a subject's eye, based on OCTdata obtained by performing optical coherence tomography on thepredetermined site, and an image deforming step of deforming thetwo-dimensional front image, by changing position of at least one pixelin the two-dimensional front image based on the three-dimensionalposition, to generate a three-dimensional front image.

In the ninth aspect of some embodiments, in the eighth aspect, thespecifying step includes a site specifying step of specifying thepredetermined site based on the OCT data, and a pixel positionspecifying step of specifying the three-dimensional positioncorresponding to a pixel of the predetermined site in thetwo-dimensional front image, based on correspondence information inwhich positions of pixels of the two-dimensional front image areassociated with A-scan positions in the predetermined site in advance.

The tenth aspect of some embodiments, in the eighth aspect or the ninthaspect, further includes a shape correcting step of correcting a shapeof the predetermined site by correcting the three-dimensional frontimage so as to follow traveling directions of measurement light.

The eleventh aspect of some embodiments, in the eighth aspect or theninth aspect, further includes a shape correcting step of correcting ashape of the predetermined site by correcting the OCT data so as tofollow traveling directions of measurement light, wherein the specifyingstep is performed to specify the three-dimensional position based ondata corrected in the shape correcting step.

The twelfth aspect of some embodiments, in any one of the eighth aspectto the eleventh aspect, further includes a designation step ofdesignating a point of view in a predetermined three-dimensionalcoordinate system, a projection step of projecting the three-dimensionalfront image onto a two-dimensional plane in the three-dimensionalcoordinate system in a line of sight direction passing through the pointof view designated in the designation step, and a display control stepof displaying an image on a display unit, the image being projected ontothe two-dimensional plane projected in the projection step.

In the thirteenth aspect of some embodiments, in any one of the eighthaspect to the twelfth aspect, the predetermined site is a fundus orvicinity of the fundus.

The fourteenth aspect of some embodiments is a program of causing acomputer to execute each step of the ophthalmic information processingmethod of any one of the eighth aspect to the thirteenth aspect.

It should be noted that the configurations according to a plurality ofaspects described above can be combined arbitrarily.

Effects of the Invention

According to the present invention, a new technique for stereoscopicallyobserving a front image of the subject's eye with a simple process canbe provided.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an example of a configurationof an ophthalmic apparatus according to embodiments.

FIG. 2 is a schematic diagram illustrating an example of a configurationof the ophthalmic apparatus according to the embodiments.

FIG. 3 is a schematic block diagram illustrating an example of theconfiguration of the ophthalmic apparatus according to the embodiments.

FIG. 4 is a schematic block diagram illustrating an example of theconfiguration of the ophthalmic apparatus according to the embodiments.

FIG. 5 is a schematic block diagram illustrating an example of theconfiguration of the ophthalmic apparatus according to the embodiments.

FIG. 6 is a schematic diagram for explaining processing performed by theophthalmic apparatus according to a comparative example of theembodiments.

FIG. 7 is a schematic diagram for explaining processing performed by theophthalmic apparatus according to the embodiments.

FIG. 8 is a schematic diagram for explaining processing performed by theophthalmic apparatus according to the embodiments.

FIG. 9 is a schematic diagram for explaining processing performed by theophthalmic apparatus according to the embodiments.

FIG. 10 is a schematic diagram illustrating an example of an operationof the ophthalmic apparatus according to the embodiments.

FIG. 11 is a schematic diagram illustrating an example of an operationof the ophthalmic apparatus according to the embodiments.

FIG. 12 is a schematic diagram illustrating an example of an operationof the ophthalmic apparatus according to the embodiments.

FIG. 13 is a schematic diagram illustrating an example of an operationof the ophthalmic apparatus according to the embodiments.

FIG. 14 is a schematic diagram illustrating an example of an operationof the ophthalmic apparatus according to a modification example of tothe embodiments.

MODES FOR CARRYING OUT THE INVENTION

Referring now to the drawings, exemplary embodiments of an ophthalmicinformation processing apparatus, an ophthalmic apparatus, an ophthalmicinformation processing method, and a program according to the presentinvention are described below. Any of the contents of the documentscited in the present specification and arbitrary known techniques may beapplied to the embodiments below.

An ophthalmic information processing apparatus according to embodimentsacquires OCT data obtained by performing optical coherence tomography ona predetermined site of a subject's eye and a two-dimensional frontimage depicting the predetermined site described above. The ophthalmicapparatus specifies a three-dimensional position of each pixel in thetwo-dimensional front image based on the acquired OCT data, and deformsthe two-dimensional front image by changing position of at least onepixel in the two-dimensional front image based on the specifiedthree-dimensional position. This allows to acquire the three-dimensionalfront image for stereoscopically observing the front image depicting thepredetermined site.

For example, by referring to correspondence information in which aposition of each pixel in the two-dimensional front image is associatedwith an A-scan position of OCT in advance, the three-dimensionalposition of each pixel in the two-dimensional front image is specified.In particular, in the case of an ophthalmic apparatus with an imagingoptical system for acquiring the two-dimensional front image and aninterference optical system for acquiring OCT data, the relationshipbetween the A-scan position of OCT and the position of each pixel in thetwo-dimensional front image is uniquely determined according to theoptical arrangement, etc.

According to such a method, the pixel position of each pixel in thetwo-dimensional front image can be transformed into thethree-dimensional position from the OCT data. Thereby, thethree-dimensional front image can be acquired with a simple process.This allows to grasp the morphology of the fundus in light of itsthree-dimensional shape, which had been determined from the color of thecolor two-dimensional fundus image, for example.

The OCT data can be acquired, for example, using an apparatus with aninterference optical system (such as an OCT apparatus). Thetwo-dimensional front image can be acquired, for example, using anapparatus with an imaging optical system (fundus camera, scanning laserophthalmoscope, etc.).

In some embodiments, the predetermined site is an anterior segment or aposterior segment. Examples of the anterior segment include a cornea, aniris, a crystalline lens, a ciliary body, and a ciliary zonule. Examplesof the posterior segment include a vitreous body, and a fundus or thevicinity of the fundus (retina, choroid, sclera, etc.).

An ophthalmic information processing method according to the embodimentsincludes one or more steps for realizing the processing executed by aprocessor (computer) in the ophthalmic information processing apparatusaccording to the embodiments. A program according to the embodimentscauses the processor to execute each step of the ophthalmic informationprocessing method according to the embodiments.

The term “processor” as used herein refers to a circuit such as, forexample, a central processing unit (CPU), a graphics processing unit(GPU), an application specific integrated circuit (ASIC), and aprogrammable logic device (PLD). Examples of PLD include a simpleprogrammable logic device (SPLD), a complex programmable logic device(CPLD), and a field programmable gate array (FPGA). The processorrealizes, for example, the function according to the embodiments byreading out a computer program stored in a storage circuit or a storagedevice and executing the computer program.

In this specification, an image acquired using OCT may be collectivelyreferred to as an “OCT image”. Also, the measurement operation forforming OCT images may be referred to as OCT measurement. Furthermore, atwo-dimensional or three-dimensional tomographic image may becollectively referred to simply as a tomographic image. Furthermore, athree-dimensional tomographic image is sometimes collectively referredto as a three-dimensional image.

Hereinafter, a case where the ophthalmic apparatus according to theembodiments has the function of the ophthalmic information processingapparatus according to the embodiments will be described. However, theophthalmic information processing apparatus according to the embodimentsmay be configured to acquire at least one of the OCT data (OCT image) ora front image from an external ophthalmic apparatus. Further, theophthalmic information processing apparatus may be configured to acquireOCT data (scan data) obtained by performing OCT measurement and to forman OCT image from the acquired OCT data.

Hereinafter, in the embodiments, a case of using the swept source typeOCT method in the measurement or the imaging (photographing) using OCTwill be described. However, the configuration according to theembodiments can also be applied to an ophthalmic apparatus using othertype of OCT (for example, spectral domain type OCT or time domain OCT).

The ophthalmic apparatus according to the embodiments includes an OCTapparatus for acquiring the OCT data and an ophthalmic imaging apparatusfor imaging a predetermined site of a subject's eye. The ophthalmicimaging apparatus includes at least one of a fundus camera, a scanninglaser ophthalmoscope, a slit lamp ophthalmoscope, a surgical microscope,or the like. The ophthalmic apparatus according to some embodimentsfurther includes at least one of an ophthalmic measuring apparatus or anophthalmic therapy apparatus. The ophthalmic measuring apparatusincludes at least one of an eye refractivity examination apparatus, atonometer, a specular microscope, a wave-front analyzer, a perimeter, ora microperimeter, for example. The ophthalmic therapy apparatus includesat least one of a laser therapy apparatus, a surgical apparatus, asurgical microscope, or the like.

The ophthalmic apparatus according to the following embodiments isassumed to include the OCT apparatus capable of performing OCTmeasurement and the fundus camera for photographing the fundus as thepredetermined site.

Hereinafter, an ophthalmic apparatus capable of performing OCTmeasurement on the fundus of the subject's eye will be described as anexample. However, the ophthalmic apparatus according to the embodimentsmay be capable of performing OCT measurement on an anterior segment ofthe subject's eye. In some embodiments, a measurement range of the OCTmeasurement and/or a site of the OCT measurement are/is changed bymoving a lens for changing focal position of measurement light. In someembodiments, the ophthalmic apparatus has a configuration capable ofperforming OCT measurement on the fundus, OCT measurement on theanterior segment, and OCT measurement on the whole eyeball including thefundus and the anterior segment, by adding one or more attachments(objective lens, front lens, etc.). In some embodiments, in theophthalmic apparatus for measuring fundus, OCT measurement is performedon the anterior segment, by making the measurement light incident on thesubject's eye, the measurement light having been converted into aparallel light flux by arranging a front lens between the objective lensand the subject's eye.

<Configuration> [Optical System]

As shown in FIG. 1 , the ophthalmic apparatus 1 includes a fundus cameraunit 2, an OCT unit 100, and an arithmetic control unit 200. The funduscamera unit 2 is provided with an optical system and a mechanism foracquiring front images of a subject's eye E. The OCT unit 100 isprovided with a part of an optical system and a mechanism for performingOCT. Another part of the optical system and the mechanism for performingOCT are provided in the fundus camera unit 2. The arithmetic controlunit 200 includes one or more processors for performing various kinds ofarithmetic processing and control processing. In addition to theseelements, an arbitrary element or a unit, such as a member (chin rest,forehead pad, etc.) for supporting a face of the subject, a lens unit(for example, an attachment for an anterior segment OCT) for switchingthe target site of OCT, and the like, may be provided in the ophthalmicapparatus 1. In some embodiments, the lens unit is configured to bemanually inserted and removed between the subject's eye E and anobjective lens 22 described below. In some embodiments, the lens unit isconfigured to be automatically inserted and removed between thesubject's eye E and the objective lens 22 described below, under thecontrol of the controller 210 described below.

In some embodiments, the ophthalmic apparatus 1 includes a displayapparatus 3. The display apparatus 3 displays a processing result (forexample, an OCT image or the like) obtained by the arithmetic controlunit 200, an image obtained by the fundus camera unit 2, operationguidance information for operating the ophthalmic apparatus 1, and thelike.

[Fundus Camera Unit]

The fundus camera unit 2 is provided with an optical system for imaging(photographing) a fundus Ef of the subject's eye E. An image (calledfundus image, fundus photograph, etc.) of the fundus Ef to be obtainedis a front image such as an observation image, a photographic image, orthe like. The observation image is obtained by moving image shootingusing near infrared light. The photographic image is a color still imageusing flash light. Furthermore, the fundus camera unit 2 can obtain thefront image (anterior segment image) by photographing (imaging) ananterior segment Ea of the subject's eye E.

The fundus camera unit 2 includes an illumination optical system 10 andan imaging (photographing) optical system 30. The illumination opticalsystem 10 projects illumination light onto the subject's eye E. Theimaging optical system 30 detects returning light of the illuminationlight from the subject's eye E. Measurement light from the OCT unit 100is guided to the subject's eye E through an optical path in the funduscamera unit 2. Returning light of the measurement light is guided to theOCT unit 100 through the same optical path.

Light (observation illumination light) emitted from the observationlight source 11 of the illumination optical system 10 is reflected by areflective mirror 12 having a curved reflective surface, and becomesnear-infrared light after being transmitted through a visible cut filter14 via a condenser lens 13. Further, the observation illumination lightis once converged near an imaging light source 15, is reflected by amirror 16, and passes through relay lenses 17 and 18, a diaphragm 19,and a relay lens 20. Then, the observation illumination light isreflected on the peripheral part (the surrounding area of a hole part)of a perforated mirror 21, is transmitted through a dichroic mirror 46,and is refracted by the objective lens 22, thereby illuminating thesubject's eye E (fundus Ef or anterior segment Ea). Returning light ofthe observation illumination light reflected from the subject's eye E isrefracted by the objective lens 22, is transmitted through the dichroicmirror 46, passes through the hole part formed in the center region ofthe perforated mirror 21, is transmitted through a dichroic mirror 55.The returning light transmitted through the dichroic mirror 55 travelsthrough a photography focusing lens 31 and is reflected by a mirror 32.Further, this returning light is transmitted through a half mirror 33A,is reflected by a dichroic mirror 33, and forms an image on the lightreceiving surface of an image sensor 35 by a condenser lens 34. Theimage sensor 35 detects the returning light at a predetermined framerate. It should be noted that the focus of the imaging optical system 30is adjusted so as to coincide with the fundus Ef or the anterior segmentEa.

Light (imaging illumination light) emitted from the imaging light source15 is projected onto the fundus Ef via the same route as that of theobservation illumination light. Returning light of the imagingillumination light from the subject's eye E is guided to the dichroicmirror 33 via the same route as that of the observation illuminationlight, is transmitted through the dichroic mirror 33, is reflected by amirror 36, and forms an image on the light receiving surface of theimage sensor 38 by a condenser lens 37.

A liquid crystal display (LCD) 39 displays a fixation target and avisual target used for visual acuity measurement. Part of light outputfrom the LCD 39 is reflected by the half mirror 33A, is reflected by themirror 32, travels through the photography focusing lens 31 and thedichroic mirror 55, and passes through the hole part of the perforatedmirror 21. The light flux (beam) having passed through the hole part ofthe perforated mirror 21 is transmitted through the dichroic mirror 46,and is refracted by the objective lens 22, thereby being projected ontothe fundus Ef.

By changing the display position of the fixation target on the screen ofthe LCD 39, the fixation position of the subject's eye E can be changed.Examples of the fixation position include a fixation position foracquiring an image centered at a macula, a fixation position foracquiring an image centered at an optic disc, a fixation position foracquiring an image centered at a fundus center between the macula andthe optic disc, a fixation position for acquiring an image of a site(fundus peripheral part) far away from the macula, and the like. Theophthalmic apparatus 1 according to some embodiments includes GUI(Graphical User Interface) and the like for designating at least one ofsuch fixation positions. The ophthalmic apparatus 1 according to someembodiments includes GUI etc. for manually moving the fixation position(display position of the fixation target).

The configuration for presenting the movable fixation target to thesubject's eye E is not limited to the display device such LCD or thelike. For example, the movable fixation target can be generated byselectively turning on a plurality of light sources of a light sourcearray (light emitting diode (LED) array or the like). Alternatively, themovable fixation target can be generated using one or more movable lightsources.

Further, the ophthalmic apparatus 1 may be provided with one or moreexternal fixation light sources. One of the one or more externalfixation light sources can project fixation light onto a fellow eye ofthe subject's eye E. A projected position of the fixation light on thefellow eye can be changed. By changing the projected position of thefixation light on the fellow eye, the fixation position of the subject'seye E can be changed. The fixation position projected by the externalfixation light source(s) may be the same as the fixation position of thesubject's eye E using the LCD 39. For example, the movable fixationtarget can be generated by selectively turning on the plurality ofexternal fixation light sources. Alternatively, the movable fixationtarget can be generated using one or more movable external fixationlight sources.

The alignment optical system 50 generates an alignment indicator foralignment of the optical system with respect to the subject's eye E.Alignment light emitted from an LED 51 travels through the diaphragms 52and 53 and the relay lens 54, is reflected by the dichroic mirror 55,and passes through the hole part of the perforated mirror 21. The lighthaving passed through the hole part of the perforated mirror 21 istransmitted through the dichroic mirror 46, and is projected onto thesubject's eye E by the objective lens 22. Corneal reflection light ofthe alignment light is guided to the image sensor 35 through the sameroute as the returning light of the observation illumination light.Manual alignment or automatic alignment can be performed based on thereceived light image (alignment indicator image) thereof.

The focus optical system 60 generates a split indicator for adjustingthe focus with respect to the subject's eye E. The focus optical system60 is movable along an optical path (illumination optical path) of theillumination optical system 10 in conjunction with the movement of thephotography focusing lens 31 along an optical path (imaging opticalpath) of the imaging optical system 30. The reflection rod 67 can beinserted and removed into and from the illumination optical path. Toperform focus adjustment, the reflective surface of the reflection rod67 is arranged in a slanted position on the illumination optical path.Focus light emitted from an LED 61 passes through a relay lens 62, issplit into two light beams by a split indicator plate 63, passes througha two-hole diaphragm 64, is reflected by a mirror 65, and is reflectedafter an image is once formed on the reflective surface of thereflection rod 67 by a condenser lens 66. Further, the focus lighttravels through the relay lens 20, is reflected by the perforated mirror21, is transmitted through the dichroic mirror 46, and is refracted bythe objective lens 22, thereby being projected onto the fundus Ef.Fundus reflection light of the focus light is guided to the image sensor35 through the same route as the corneal reflection light of thealignment light. Manual focus or automatic focus can be performed basedon the received light image (split indicator image) thereof.

The dichroic mirror 46 combines an optical path for fundus photographyand an optical path for OCT. The dichroic mirror 46 reflects light ofwavelength band used in OCT, and transmits light for fundus imaging. Theoptical path for OCT (optical path of measurement light) is providedwith, in order from the OCT unit 100 side to the dichroic mirror 46side, a collimator lens unit 40, an optical path length changing unit41, an optical scanner 42, an OCT focusing lens 43, a mirror 44, and arelay lens 45.

The optical path length changing unit 41 is movable in directionsindicated by the arrow in FIG. 1 , thereby changing the length of theoptical path for OCT. This change in the optical path length is used forcorrecting the optical path length according to the axial length,adjusting the interference state, or the like. The optical path lengthchanging unit 41 includes a corner cube and a mechanism for moving thecorner cube.

The optical scanner 42 is disposed at a position optically conjugate tothe pupil of the subject's eye E. The optical scanner 42 deflects themeasurement light traveling along the OCT optical path. That is, theoptical scanner 42 deflects the measurement light for scanning insidethe subject's eye E while changing the scan angle within a predetermineddeflection angle range with the pupil (or the vicinity thereof) of thesubject's eye E as the scan center position. The optical scanner 42 candeflect the measurement light in a one-dimensionally or two-dimensionalmanner.

In case that the optical scanner 42 deflects the measurement light in aone-dimensionally manner, the optical scanner 42 includes a galvanoscanner capable of deflecting the measurement light in a predetermineddeflection direction within a predetermined deflection angle range. Incase that the optical scanner deflects the measurement light LS in atwo-dimensionally manner, the optical scanner 42 includes a firstgalvano scanner and a second galvano scanner. The first galvano scannerdeflects the measurement light so as to scan a photographing (imaging)site (fundus Ef or the anterior segment Ea) in a horizontal directionorthogonal to the optical axis of the OCT optical system 8. The secondgalvano scanner deflects the measurement light deflected by the firstgalvano mirror so as to scan the photographing site in a verticaldirection orthogonal to the optical axis of the OCT optical system 8.Examples of scan mode with the measurement light performed by theoptical scanner 42 include horizontal scan, vertical scan, cross scan,radial scan, circle scan, concentric scan, helical (spiral) scan, andthe like.

The OCT focusing lens 43 is moved along the optical path of themeasurement light in order to perform focus adjustment of the opticalsystem for OCT. The OCT focusing lens 43 can be moved within a movingrange. The moving range includes a first lens position for placing thefocal position of the measurement light at the fundus Ef or near thefundus Ef of the subject's eye E and a second lens position for makingthe measurement light projected onto the subject's eye E a parallellight beam. The movement of the photography focusing lens 31, themovement of the focus optical system 60, and the movement of the OCTfocusing lens 43 can be controlled in conjunction with each other.

[Oct Unit]

An example of the configuration of the OCT unit 100 is shown in FIG. 2 .The OCT unit 100 is provided with an optical system for acquiring OCTdata (OCT images) of the subject's eye E. The optical system includes aninterference optical system that splits light from a wavelength sweepingtype (i.e., a wavelength scanning type) light source into measurementlight and reference light, makes the measurement light returning fromthe subject's eye E and the reference light having traveled through thereference optical path interfere with each other to generateinterference light, and detects the interference light. The detectionresult of the interference light obtained by the interference opticalsystem (i.e., the detection signal) is an interference signal indicatingthe spectrum of the interference light, and is sent to the arithmeticcontrol unit 200.

Like swept source type ophthalmic apparatuses commonly used, the lightsource unit 101 includes a wavelength sweeping type (i.e., a wavelengthscanning type) light source capable of sweeping (scanning) thewavelengths of emitted light. The wavelength sweeping type light sourceincludes a laser light source that includes a resonator. The lightsource unit 101 temporally changes the output wavelengths within thenear-infrared wavelength bands that cannot be visually recognized withhuman eyes.

Light LO output from the light source unit 101 is guided to thepolarization controller 103 through the optical fiber 102, and thepolarization state of the light LO is adjusted. The polarizationcontroller 103, for example, applies external stress to the loopedoptical fiber 102 to thereby adjust the polarization state of the lightLO guided through the optical fiber 102.

The light LO whose the polarization state has been adjusted by thepolarization controller 103 is guided to the fiber coupler 105 throughthe optical fiber 104, and is split into the measurement light LS andthe reference light LR.

The reference light LR is guided to the collimator 111 through theoptical fiber 110. The reference light LR is converted into a parallellight beam by the collimator 111. Then, the reference light LR is guidedto the optical path length changing unit 114 via an optical path lengthcorrection member 112 and a dispersion compensation member 113. Theoptical path length correction member 112 acts so as to match theoptical path length of the reference light LR with the optical pathlength of the measurement light LS. The dispersion compensation member113 acts so as to match the dispersion characteristics between thereference light LR and the measurement light LS.

The optical path length changing unit 114 is movable in directionsindicated by the arrow in FIG. 2 , thereby changing the length of theoptical path of the reference light LR. Through such movement, thelength of the optical path of the reference light LR is changed. Thechange in the optical path length is used for the correction of theoptical path length according to the axial length of the subject's eyeE, for the adjustment of the interference state, or the like. Theoptical path length changing unit 114 includes, for example, a cornercube and a movement mechanism for moving the corner cube. In this case,the corner cube in the optical path length changing unit 114 changes thetraveling direction of the reference light LR that has been made intothe parallel light flux by the collimator 111 in the opposite direction.The optical path of the reference light LR incident on the corner cubeand the optical path of the reference light LR emitted from the cornercube are parallel.

The reference light LR that has traveled through the optical path lengthchanging unit 114 passes through the dispersion compensation member 113and the optical path length correction member 112, is converted from theparallel light beam to the convergent light beam by a collimator 116,and enters an optical fiber 117. The reference light LR that has enteredthe optical fiber 117 is guided to the polarization controller 118. Withthe polarization controller 118, the polarization state of the referencelight LR is adjusted. The polarization controller 118 has the sameconfiguration as, for example, the polarization controller 103. Thereference light LR whose the polarization state has been adjusted by thepolarization controller 118 is guided to the attenuator 120 through theoptical fiber 119, and the light amount thereof is adjusted by theattenuator 120 under the control of the arithmetic control unit 200. Thereference light LR whose light amount has been adjusted by theattenuator 120 is guided to the fiber coupler 122 through the opticalfiber 121.

The configuration shown in FIG. 1 and FIG. 2 includes both the opticalpath length changing unit 41 that changes the length of the optical pathof the measurement light LS (i.e., measurement optical path ormeasurement arm) and the optical path length changing unit 114 thatchanges the length of the optical path of the reference light LR (i.e.,reference optical path or reference arm). However, any one of theoptical path length changing units 41 and 114 may be provided. Thedifference between the measurement optical path length and the referenceoptical path length can be changed by using other optical members.

Meanwhile, the measurement light LS generated by the fiber coupler 105is guided through the optical fiber 127, and is made into the parallellight beam by the collimator lens unit 40. The measurement light LS madeinto the parallel light flux is guided to the dichroic mirror 46 via theoptical path length changing unit 41, the optical scanner 42, the OCTfocusing lens 43, the mirror 44, and the relay lens 45. The measurementlight LS guided to the dichroic mirror 46 is reflected by the dichroicmirror 46, refracted by the objective lens 22, and projected onto thesubject's eye E. The measurement light LS is scattered (and reflected)at various depth positions of the subject's eye E. The returning lightof the measurement light LS including such backscattered light advancesthrough the same path as the outward path in the opposite direction andis led to the fiber coupler 105, and then reaches the fiber coupler 122through the optical fiber 128.

The fiber coupler 122 combines (interferes) the measurement light LSincident through the optical fiber 128 and the reference light LRincident through the optical fiber 121 to generate interference light.The fiber coupler 122 generates a pair of interference light LC bysplitting the interference light generated from the measurement light LSand the reference light LR at a predetermined splitting ratio (forexample, 1:1). The pair of the interference light LC emitted from thefiber coupler 122 is guided to the detector 125 through the opticalfibers 123 and 124, respectively.

The detector 125 is, for example, a balanced photodiode that includes apair of photodetectors for respectively detecting the pair ofinterference light LC and outputs the difference between the pair ofdetection results obtained by the pair of photodetectors. The detector125 sends the detection result (i.e., interference signal) to the DAQ(data acquisition system) 130. A clock KC is supplied from the lightsource unit 101 to the DAQ 130. The clock KC is generated in the lightsource unit 101 in synchronization with the output timing of eachwavelength sweeping (scanning) within a predetermined wavelength rangeperformed by the wavelength sweeping type light source. For example, thelight source unit 101 optically delays one of the two pieces of branchedlight obtained by branching the light LO of each output wavelength, andthen generates the clock KC based on the result of the detection of thecombined light of the two pieces of branched light. The DAQ 130 performssampling of the detection result obtained by the detector 125 based onthe clock KC. The DAQ 130 sends the result of the sampling of thedetection result obtained by the detector 125 to the arithmetic controlunit 200. For example, the arithmetic control unit 200 performs theFourier transform etc. on the spectral distribution based on thedetection result obtained by the detector 125 for each series ofwavelength scanning (i.e., for each A-line). With this, the reflectionintensity profile for each A-line is formed. In addition, the arithmeticcontrol unit 200 forms image data by applying imaging processing to thereflection intensity profiles for the respective A-lines.

[Arithmetic Control Unit]

The arithmetic control unit 200 analyzes the detection signals fed fromthe DAQ 130 to form an OCT image or scan data of the fundus Ef (or theanterior segment Ea). The arithmetic processing therefor is performed inthe same manner as in the conventional swept-source-type OCT apparatus.

Further, the arithmetic control unit 200 controls each part of thefundus camera unit 2, the display apparatus 3, and the OCT unit 100.

Also, as the control of the fundus camera unit 2, the arithmetic controlunit 200 performs following controls: the operation control of theobservation light source 11, the operation control of the imaging lightsource 15 and the operation control of the LEDs 51 and 61; the operationcontrol of the LCD 39; the movement control of the photography focusinglens 31; the movement control of the OCT focusing lens 43; the movementcontrol of the reflection rod 67; the movement control of the focusoptical system 60; the movement control of the optical path lengthchanging unit 41; the operation control of the optical scanner 42, andthe like.

As the control of the display apparatus 3, the arithmetic control unit200 controls the display apparatus 3 to display the OCT image of thesubject's eye E.

As the control of the OCT unit 100, the arithmetic control unit 200controls: the operation of the light source unit 101; the operation ofthe optical path length changing unit 114; the operations of theattenuator 120; the operation of the polarization controllers 103 and118; the operation of the detector 125; the operation of the DAQ 130;and the like.

As in the conventional computer, the arithmetic control unit 200includes a processor, RAM, ROM, hard disk drive, and communicationinterface, for example. A storage device such as the hard disk drivestores a computer program for controlling the ophthalmic apparatus 1.The arithmetic control unit 200 may include various kinds of circuitrysuch as a circuit board for forming OCT images. In addition, thearithmetic control unit 200 may include an operation device (or an inputdevice) such as a keyboard and a mouse, and a display device such as anLCD.

The fundus camera unit 2, the display apparatus 3, the OCT unit 100, andthe arithmetic control unit 200 may be integrally provided (i.e., in asingle housing), or they may be separately provided in two or morehousings.

[Control System]

FIGS. 3 to 5 illustrate configuration examples of a control system ofthe ophthalmic apparatus 1. In FIGS. 3 to 5 , a part of the componentsincluded in the ophthalmic apparatus 1 is omitted.

The arithmetic control unit 200 includes a controller 210.

(Controller)

The controller 210 executes various controls. The controller 210includes a main controller 211 and a storage unit 212.

(Main Controller)

The main controller 211 includes a processor and controls each part ofthe ophthalmic apparatus 1. For example, the main controller 211controls components of the fundus camera unit 2 such as focusing drivers31A and 43A, the image sensors 35 and 38, the LCD 39, the optical pathlength changing unit 41, the optical scanner 42, and a movementmechanism 150 for moving the optical system. Further, the maincontroller 211 controls components of the OCT unit 100 such as the lightsource unit 101, the optical path length changing unit 114, theattenuator 120, the polarization controllers 103 and 118, the detector125, and the DAQ 130.

For example, the main controller 211 controls the LCD 39 to display thefixation target at a position on the screen of the LCD 39 correspondingto the fixation position set manually or automatically. Moreover, themain controller 211 can change the display position of the fixationtarget displayed on the LCD 39 (in a continuous manner or in a phasedmanner). Thereby, the fixation target can be moved (that is, thefixation position can be changed). The display position of the fixationtarget and movement mode of the fixation target are set manually orautomatically. Manual setting is performed using GUI, for example.Automatic setting is performed by the data processor 230, for example.

The focusing driver 31A moves the photography focusing lens 31 in thedirection along the optical axis of the imaging optical system 30, andmoves the focus optical system 60 in the direction along the opticalaxis of the illumination optical system 10. With this, the focusposition of the imaging optical system 30 is changed. The focusingdriver 31A may include a dedicated mechanism for moving the photographyfocusing lens 31 and a dedicated mechanism for moving the focus opticalsystem 60. The focusing driver 31A is controlled when performing focusadjustment or the like.

The focusing driver 43A moves the OCT focusing lens 43 in the opticalaxis direction of the measurement optical path. As a result, the focusposition of the measurement light LS is changed. For example, the focusposition of the measurement light LS can be arranged at the fundus Ef ornear the fundus Ef by moving the OCT focusing lens 43 to the first lensposition. For example, the focus position of the measurement light LScan be arranged at a far point position by moving the OCT focusing lens43 to the second lens position. The focus position of the measurementlight LS corresponds to the depth position (z position) of the beamwaist of the measurement light LS.

The movement mechanism 150 three-dimensionally moves at least the funduscamera unit 2 (optical system), for example. In a typical example, themovement mechanism 150 includes a mechanism for moving at least thefundus camera unit 2 in the x direction (left-right direction), amechanism for moving it in the y direction (up-down direction), and amechanism for moving it in the z direction (depth direction, front-backdirection, optical axis direction of the optical system). The mechanismfor moving in the x direction includes a x stage movable in the xdirection and a x movement mechanism for moving the x stage, forexample. The mechanism for moving in the y direction includes a y stagemovable in the y direction and a y movement mechanism for moving the ystage, for example. The mechanism for moving in the z direction includesa z stage movable in the z direction and a z movement mechanism formoving the z stage, for example. Each movement mechanism includes anactuator such as a pulse motor, and operates under the control of themain controller 211.

The control for the movement mechanism 150 is used for alignment andtracking. Here, tracking is to move the optical system of the apparatusaccording to the movement of the subject's eye E. To perform tracking,alignment and focus adjustment are performed in advance. The tracking isa function of maintaining a suitable positional relationship in whichalignment and focusing are matched by causing the position of theoptical system of the apparatus and the like to follow the eye movement.In some embodiments, the movement mechanism 150 is configured to becontrolled to change the optical path length of the reference light(that is, the difference of the optical path length between the opticalpath of the measurement light and the optical path of the referencelight).

In the case of manual alignment, a user operates a user interface (UI)240 described below to relatively move the optical system and subject'seye E so as to cancel the displacement of the subject's eye E withrespect to the optical system. For example, the main controller 211controls the movement mechanism 150 to relatively move the opticalsystem and the subject's eye E by outputting a control signalcorresponding to the operation content with respect to the userinterface 240 to the movement mechanism 150.

In the case of automatic alignment, the main controller 211 controls themovement mechanism 150 to relatively move the optical system and thesubject's eye E so as to cancel the displacement of the subject's eye Ewith respect to the optical system. For example, the movement mechanism150 is controlled so as to cancel a displacement between (a referenceposition of) the image of the subject's eye E acquired using imagingoptical system (not shown) and a reference position of the opticalsystem. In some embodiments, the main controller 211 controls themovement mechanism 150 to relatively move the optical system and thesubject's eye E by outputting a control signal to the movement mechanism150 so that the optical axis of the optical system substantiallycoincides with the axis of the subject's eye E and the distance of theoptical system with respect to the subject's eye E is a predeterminedworking distance. Here, the working distance is a preset value which iscalled a working distance of the objective lens 22, and it means thedistance between the subject's eye E and the optical system whenmeasuring (imaging) using the optical system.

The main controller 211 controls the fundus camera unit 2 etc. tocontrol the fundus imaging (photography) and the anterior segmentimaging. Further, the main controller 211 controls the fundus cameraunit 2 and the OCT unit 100 etc. to control the OCT measurement. Themain controller 211 is capable of performing a plurality of preliminaryoperations prior to OCT measurement. Examples of the preliminaryoperation include alignment, rough focus adjustment, polarizationadjustment, and fine focus adjustment. The plurality of preliminaryoperations is performed in a predetermined order. In some embodiments,the plurality of preliminary operations is performed in an orderdescribed above.

It should be noted that the types and the orders of the preliminaryoperations are not so limited, and they may be optional. For example,the preliminary operations may further include small-pupil judgment. Thesmall-pupil judgment is a preliminary operation to judge whether thepupil of the subject's eye E is small or not (whether the subject's eyeE is microcoria or not). The small-pupil judgment may be performedbetween the rough focus adjustment and the optical path lengthdifference adjustment. In some embodiments, the small-pupil judgmentincludes, for example, a series of processes as follows: acquiring afront image (anterior segment image) of the subject's eye E; specifyingan image region corresponding to the pupil; calculating the size (e.g.,diameter, circumference length) of the pupil region; judging whether thepupil of the subject's eye E is small or not based on the calculatedsize (threshold processing); and controlling the diaphragm 19 whenjudged that the pupil of the subject's eye E is small. In someembodiments, the calculation of the size of the pupil region includesprocessing of circularly or elliptically approximating the pupil region.

The rough focus adjustment is a kind of focus adjustment using the splitindicator. The rough focus adjustment may be performed by determiningthe position of the photography focusing lens 31 based on information,which is obtained by associating the eye refractive power acquired inadvance with the position of the photography focusing lens 31, and ameasured value of the refractive power of the subject's eye E.

The fine focus adjustment is performed on the basis of interferencesensitivity of OCT measurement. For example, the fine focus adjustmentcan be performed by: monitoring interference intensity (interferencesensitivity) of interference signal acquired by performing OCTmeasurement of the subject's eye E; searching the position of the OCTfocusing lens 43 so as to maximize the interference intensity; andmoving the OCT focusing lens 43 to the searched position.

To perform the optical path length difference adjustment, the opticalsystem is controlled so that a predetermined position on the subject'seye E is a reference position of a measurement range in the depthdirection. The control is performed on at least one of the optical pathlength changing units 41 and 114. Thereby, the difference of the opticalpath length between the measurement optical path and the referenceoptical path is adjusted. By setting the reference position in theoptical path length difference adjustment, OCT measurement can beperformed with high accuracy over a desired measurement range in thedepth direction simply by changing the wavelength sweep speed.

To perform the polarization adjustment, the polarization state of thereference light LR is adjusted for optimizing the interferenceefficiency between the measurement light LS and the reference light LR.

(Storage Unit)

The storage unit 212 stores various types of data. Examples of the datastored in the storage unit 212 include image data of an OCT image, imagedata of a fundus image, scan data, image data of an anterior segmentimage, and subject's eye information. The subject's eye informationincludes information on the subject such as patient ID and name, andinformation on the subject's eye such as identification information ofthe left eye/right eye.

The storage unit 212 also stores correspondence information 212A. Thecorrespondence information 212A is information in which the position ofeach pixel in the fundus image (two-dimensional front image) obtainedusing the imaging optical system 30 is, in advance, associated with theA-scan position of the OCT (incident position of the measurement lightLS) on the predetermined site (here, fundus). In the ophthalmicapparatus 1, the relationship between the A-scan position by the OCTunit 100 and the position of each pixel in the fundus image obtainedusing the imaging optical system 30 is uniquely determined in accordancewith the arrangement of the optical elements in each optical system,etc. In some embodiments, the correspondence information 212A is updatedin accordance with the arrangement state of the optical elements, in theinspection process at the time of manufacture and shipment of theophthalmic apparatus 1 or in the predetermined adjustment process aftershipment.

Further, the storage unit 212 can store an eyeball parameter. Theeyeball parameter includes a parameter (standard value) defined by aknown eyeball model such as a Gullstrand schematic eye. In someembodiments, the eyeball parameter includes a parameter in which atleast one of the parameters defined by a known eyeball model is replacedwith the measured value of the subject's eye E. In this case, it meansthat the eyeball parameter includes a parameter representing opticalcharacteristics of the subject's eye E. Examples of the measured valueinclude an axial length, a corneal thickness, a curvature radius of ananterior surface of cornea, a curvature radius of a posterior surface ofcornea, an anterior chamber depth, a curvature radius of an anteriorsurface of a lens, a lens thickness, a curvature radius of a posteriorsurface of lens, a vitreous cavity length, a retinal thickness, and achoroid thickness. In some embodiments, the measured value is acquiredby analyzing OCT data obtained by performing OCT measurement. Theeyeball parameter may include a parameter designated using the operationunit 240B described below.

In addition, the storage unit 212 stores various kinds of computerprograms and data for operating the ophthalmic apparatus 1.

(Image Forming Unit)

The image forming unit 220 performs signal processing such as theFourier transform on sampling data obtained by sampling the detectionsignal from the detector 125 in the DAQ 130. With this, the reflectionintensity profile for each A-line is formed. The above signal processingincludes noise removal (noise reduction), filtering, fast Fouriertransform (FFT), and the like. The reflection intensity profile for theA-line is an example of the A-scan data. The image forming unit 220 canform the reflection intensity profile for each A-line, and form B-scandata (two-dimensional scan data) by arranging a formed plurality ofreflection intensity profiles in the B-scan direction (intersectingdirection of the A-scan direction).

In some embodiments, the image forming unit 220 (or data processor 230described below) forms C-scan data (three-dimensional scan data) byarranging the plurality of reflection intensity profiles formed for eachA-line in the B-scan direction (for example, x direction) and adirection intersecting both of the A-scan direction and the B-scandirection (C-scan direction, for example, y direction).

Further, the image forming unit 220 can form A-scan image (OCT image,image data) of the subject's eye E, by applying imaging processing tothe reflection intensity profile in the A-line. The image forming unit220 can form a B-scan image by arranging the plurality of A-scan imagesformed for each A-line in the B-scan direction (intersecting directionof the A-scan direction). The image forming unit 220 can form athree-dimensional OCT image by arranging the plurality of B-scan imagesin the C-scan direction.

In some embodiments, the image forming unit 220 extracts data at apredetermined depth position (scan position) in each A-scan data, andforms C-scan data by arranging the extracted plurality of data in theB-scan direction (intersecting direction of the A-scan direction). Insome embodiments, the image forming unit 220 extracts a pixel at apredetermined depth position (scan position) in each A-scan image, andforms a C-scan image by arranging the extracted plurality of pixels inthe B-scan direction (intersecting direction of the A-scan direction).

In some embodiments, the function of the image forming unit 220 isrealized by a processor. It should be noted that “image data” and an“image” based on the image data may not be distinguished from each otherin the present specification.

(Data Processor)

The data processor 230 processes data acquired through photography ofthe subject's eye E or data acquired through OCT measurement.

For example, the data processor 230 performs various kinds of imageprocessing and various kinds of analysis processing on the image formedby the image forming unit 220. For example, the data processor 230performs various types of image correction processing such as brightnesscorrection. The data processor 230 performs various kinds of imageprocessing and various kinds of analysis processing on images capturedby the fundus camera unit 2 (e.g., fundus images, anterior segmentimages, etc.).

The data processor 230 performs known image processing such asinterpolation for interpolating pixels in tomographic images to formthree-dimensional image data of the fundus Ef. Note that image data ofthe three-dimensional image means image data in which the positions ofpixels are defined by a three-dimensional coordinate system. Examples ofthe image data of the three-dimensional image include image data definedby voxels three-dimensionally arranged. Such image data is referred toas volume data or voxel data. When displaying an image based on volumedata, the data processor 230 performs rendering (volume rendering,maximum intensity projection (MIP), etc.) on the volume data, therebyforming image data of a pseudo three-dimensional image viewed from aparticular line of sight. The pseudo three-dimensional image isdisplayed on the display device such as a display unit 240A.

The three-dimensional image data may be stack data of a plurality oftomographic images. The stack data is image data formed bythree-dimensionally arranging tomographic images along a plurality ofscan lines based on positional relationship of the scan lines. That is,the stack data is image data formed by representing tomographic images,which are originally defined in their respective two-dimensionalcoordinate systems, by a single three-dimensional coordinate system.That is, the stack data is image data formed by embedding tomographicimages into a single three-dimensional space.

The data processor 230 can form a B-mode image (longitudinalcross-sectional image, axial cross-sectional image) in an arbitrarycross section, a C-mode image (transverse section image, horizontalcross-sectional image) in an arbitrary cross section, a projectionimage, a shadowgram, etc., by performing various renderings on theacquired three-dimensional data set (volume data, stack data, etc.). Animage in an arbitrary cross section such as a B-mode image or a C-modeimage is formed by selecting pixels (voxels) on a designated crosssection from the three-dimensional data set. The projection image isformed by projecting the three-dimensional data set in a predetermineddirection (z direction, depth direction, axial direction).

The shadowgram is formed by projecting a part of the three-dimensionaldata set in a predetermined direction. Examples of the part of thethree-dimensional data set include partial data corresponding to aspecific layer. An image having a viewpoint on the front side of thesubject's eye, such as the C-mode image, the projection image, and theshadowgram, is called a front image (en-face image).

The data processor 230 can build (form) the B-mode image or the frontimage (blood vessel emphasized image, angiogram) in which retinal bloodvessels and choroidal blood vessels are emphasized (highlighted), basedon data (for example, B-scan image data) acquired in time series by OCT.For example, the OCT data in time series can be acquired by repeatedlyscanning substantially the same site of the subject's eye E.

In some embodiments, the data processor 230 compares the B-scan imagesin time series acquired by B-scan for substantially the same site,converts the pixel value of a change portion of the signal intensityinto a pixel value corresponding to the change portion, and builds theemphasized image in which the change portion is emphasized. Further, thedata processor 230 forms an OCTA image by extracting information of apredetermined thickness at a desired site from a plurality of builtemphasized images and building as an en-face image.

An image (for example, a three-dimensional image, a B-mode image, aC-mode image, a projection image, a shadowgram, and an OCTA image)generated by the data processor 230 is also included in the OCT image.

Further, the data processor 230 determines the focus state of themeasurement light LS in fine focus adjustment control by analyzing thedetection result of the interference light obtained by the OCTmeasurement. For example, the main controller 211 performs repetitiveOCT measurements while controlling the focusing driver 43A according toa predetermined algorithm. The data processor 230 analyzes detectionresults of interference light LC repeatedly acquired by the OCTmeasurements to calculate predetermined evaluation values relating toimage quality of OCT images. The data processor 230 determines whetherthe calculated evaluation value is equal to or less than a threshold. Insome embodiments, the fine focus adjustment is continued until thecalculated evaluation value becomes equal to or less than the threshold.That is, when the evaluation value is equal to or less than thethreshold, it is determined that the focus state of the measurementlight LS is appropriate. And the fine focus adjustment is continueduntil it is determined that the focus state of the measurement light LSis appropriate.

In some embodiments, the main controller 211 monitors the intensity ofthe interference signal (interference intensity, interferencesensitivity) acquired sequentially while acquiring the interferencesignal by performing the repetitive OCT measurements as described above.In addition, while performing this monitoring process, the OCT focusinglens 43 is moved to find the position of the OCT focusing lens 43 inwhich the interference intensity is maximized. With the fine focusadjustment thus performed, the OCT focusing lens 43 can be guided to theposition where the interference intensity is optimized.

Further, the data processor 230 determines the polarization state of atleast one of the measurement light LS and the reference light LR byanalyzing the detection result of the interference light obtained by theOCT measurement. For example, the main controller 211 performsrepetitive OCT measurements while controlling at least one of thepolarization controllers 103 and 118 according to a predeterminedalgorithm. In some embodiments, the main controller 211 controls theattenuator 120 to change an attenuation of the reference light LR. Thedata processor 230 analyzes detection results of interference light LCrepeatedly acquired by the OCT measurements to calculate predeterminedevaluation values relating to image quality of OCT images. The dataprocessor 230 determines whether the calculated evaluation value isequal to or less than a threshold. The threshold is set in advance.Polarization adjustment is continued until the evaluation valuecalculated becomes equal to or less than the threshold. That is, whenthe evaluation value is equal to or less than the threshold, it isdetermined that the polarization state of the measurement light LS isappropriate. And the polarization adjustment is continued until it isdetermined that the polarization state of the measurement light LS isappropriate.

In some embodiments, the main controller 211 can monitor theinterference intensity also in the polarization adjustment.

Further, the data processor 230 performs predetermined analysisprocessing on the detection result of the interference light acquired byperforming OCT measurement or the OCT image formed based on thedetection result. Examples of the predetermined analysis processinginclude specifying (identification) of a predetermined site (tissue,lesion) of the subject's eye E; calculation of a distance, area, angle,ratio, or density between designated sites (distance between layers,interlayer distance); calculation by a designated formula; specifying ofthe shape of a predetermined site; calculation of these statistics;calculation of distribution of the measured value or the statistics;image processing based on these analysis processing results, and thelike. Examples of the predetermined tissue include a blood vessel, anoptic disc, a fovea, a macula, and the like. Examples of thepredetermined lesion include a leukoma, a hemorrhage, and the like.

The data processor 230 can perform coordinate transformation of thepixel positions in the OCT image so that the site in the eye in theacquired OCT image is drawn in actual shape.

That is, the data processor 230 corrects the OCT image (ortwo-dimensional or three-dimensional scan data) of the subject's eyeobtained by scanning inside the eye with the measurement light using theoptical scanner arranged at a position substantially optically conjugateto a predetermined scan center position in the subject's eye E. Examplesof the predetermined scan center position include a pupil. For example,the OCT image is formed by arranging a plurality of A-scan imagesacquired by scanning inside the subject's eye with the measurement lightdeflected around the pupil of the subject's eye as a scan centerposition. For example, the two-dimensional or three-dimensional scandata is formed by arranging a plurality of A-scan data acquired byscanning inside the subject's eye with the measurement light deflectedaround the pupil of the subject's eye as a scan center position.

The data processor 230 specifies a transformed position along an A-scandirection (traveling direction of the measurement light passing throughthe scan center position). Here, the transformed position corresponds toa pixel position in the OCT image (or a scan position in thetwo-dimensional or three-dimensional scan data). The data processor 230transforms the pixel position (or scan position) into the transformedposition specified based on the pixel position or the like. Thetransformed position is a position in a predetermined coordinate system.The predetermined coordinate system is defined by two or more coordinateaxes including an coordinate axis in the same axial direction as thescan direction of at least one A-scan.

In some embodiments, the data processor 230 specifies the transformedposition based on a parameter representing optical characteristics ofthe subject's eye E. In some embodiments, the data processor 230specifies at least one of a component of a first axis direction of thetransformed position or a component of a second axis direction of thetransformed position, the second axis direction intersecting the firstaxis direction, in a predetermined coordinate system, based on a scanradius in the A-scan direction, a scan angle, a depth range that can bemeasured using OCT and the pixel position (or scan position).

This allows to correct the shape of the site in the eye such as thefundus represented in the OCT image (or scan data) to the shape alongthe direction of the actual scan. In particular, the actual shape can beeasily grasped from the OCT image (or scan data), which is acquiredusing a wide-angle imaging system or an observation system. Further,morphology information representing the morphology of the subject's eyecan also be acquired as the information representing the actualmorphology, using the corrected OCT image (or two-dimensional orthree-dimensional scan data).

Further, the data processor 230 can obtain a distance betweenpredetermined sites in the eye using the OCT image after coordinatetransformation.

In addition, in order to deform the front image into a stereoscopicimage, the data processor 230 can specify the three-dimensional positionof each pixel in the two-dimensional front image, which depicts thepredetermined site such as the fundus, such as a fundus image, based onthe OCT data obtained by performing OCT measurement, and can change atleast one the position of the pixel in the two-dimensional front imagebased on the specified three-dimensional image. This allows to generatea three-dimensional front image obtained by deforming thetwo-dimensional front image. In some embodiments, the data processor 230specifies the three-dimensional position of each pixel in thetwo-dimensional front image based on the OCT data in which the shape iscorrected as described above. In some embodiments, the data processor230 corrects the shape as described above for the generatedthree-dimensional front image.

Such the data processor 230 includes a site specifying unit 231, a pixelposition specifying unit 232, a shape correcting unit 233, an imagedeforming unit 234, and a projection unit 235, as shown in FIG. 4 . Thedata processor 230 includes one or more processors that realize at leastone function of the site specifying unit 231, the pixel positionspecifying unit 232, the shape correcting unit 233, the image deformingunit 234, or the projection unit 235.

(Site Specifying Unit)

The site specifying unit 231 specifies the fundus based on the OCT data.Specifically, the site specifying unit 231 specifies a predeterminedlayer region (or boundary of the predetermined layer region) in thefundus. Examples of the predetermined layer region include a retinalpigment epithelium, an inner limiting membrane, a sclera, and a choriod.In some embodiments, the site specifying unit 231 specifies a signalposition corresponding to the fundus in each A-scan data. In someembodiments, the site specifying unit 231 specifies the position wherethe sum of the intensity values of signals for a predetermined pixels ofeach A-scan data is the maximum, as the fundus. In some embodiments, thesite specifying unit 231 specifies the layer region corresponding to thefundus from a plurality of layer regions obtained by performingsegmentation processing on the OCT data.

(Pixel Position Specifying Unit)

The pixel position specifying unit 232 refers to the correspondenceinformation 212A to specify the three-dimensional position correspondingto each pixel in the fundus image depicting the fundus specified by thesite specifying unit 231. As described above, in the correspondenceinformation 212A, the position of each pixel in the fundus image isassociated with the position of each A-scan of OCT performed on thefundus. This allows the pixel position specifying unit 232 to specifythe three-dimensional position corresponding to the position of eachpixel in the fundus image, based on the three-dimensional OCT data.

(Shape Correcting Unit)

The shape correcting unit 233 performs coordinate transformation of thepixel position so that the site inside the eye in the image is depictedwith the actual shape, as described above. In the present embodiment,the shape correcting unit 233 performs coordinate transformation of thethree-dimensional position specified by the pixel position specifyingunit 232. Hereinafter, for convenience of explanation, the coordinatetransformation of the two-dimensional pixel positions will be described.And then, the coordinate transformation of the three-dimensional pixelpositions will be described.

FIG. 6 shows a diagram of a comparative example of the embodiments. FIG.6 schematically shows the path of the measurement light incident on thesubject's eye E.

The measurement light deflected by the optical scanner 42, for example,is incident on the pupil of the subject's eye E, which is a scan centerposition, at various incident angles, as shown in FIG. 6 . Themeasurement light incident on the subject's eye E is projected towardeach part in the eye around the scan center position Cs set at thecenter of the pupil, for example.

An A-scan image is formed from the interference data obtained using themeasurement light LS1 in FIG. 6 , an A-scan image is formed from theinterference data obtained using the measurement light LS2, and anA-scan image is formed from the interference data obtained using themeasurement light LS3. The tomographic image is formed by arranging theplurality of A-scan images formed like this in the horizontal direction.

In this way, the A-scan directions vary within the scan angle rangecentered on the scan center position Cs, and the shape of the site isdeformed in the tomographic images in which the obtained plurality ofA-scan images are arranged in the horizontal direction. The wider theangle of view is, the greater the difference from the actual shapebecomes.

Further, morphology information representing the morphology of thesubject's eye E can be obtained from the positions of arbitrary pixelsin the tomographic image. Examples of the morphology information includean intraocular distance (including a distance between layer regions), anarea of region, a volume of region, a perimeter of region, a directionof site with reference to a reference position, an angle of site withreference to a reference direction, and a curvature radius of site.

For example, the intraocular distance as the morphology information canbe obtained by measuring a distance between arbitrary two points in thetomographic image. In this case, the distance between the two points canbe specified using the number of pixels in the tomographic image, andcan be measured by multiplying the specified number of pixels by thepixel size specific to the apparatus. In this case, the same pixel sizeis adopted for all pixels in the tomographic image. However, asdescribed above, the scan directions are different with the scan centerposition Cs as the center. Thereby, the pixel size in the horizontaldirection of the tomographic image differs depending on the depthposition in the scan direction. For example, in case that the depthrange is 2.5 millimeters, when the same pixel size is adopted for allpixels in the tomographic image, there is a difference of about 13% inthe scan length of the B-scan between the upper portion and the lowerportion of the tomographic image, and when the depth range is 10millimeters, there is a difference of about 50%.

In contrast, the data processor 230 according to the embodimentsperforms coordinate transformation on the pixel positions in theacquired OCT image (or scan positions in the scan data).

As shown in FIG. 5 , the shape correcting unit 233 includes atransformed position specifying unit 233A, a transforming unit 233B, andan interpolating unit 233C.

(Transformed Position Specifying Unit)

The transformed position specifying unit 233A specifies a transformedposition along the traveling direction of the measurement light passingthrough the scan center position Cs, the transformed positioncorresponding to the pixel position in the OCT image (or the scanposition in the scan data). In some embodiments, the transformedposition specifying unit 233A uses the eyeball parameter for performingprocessing for specifying the transformed position.

FIG. 7 shows a diagram describing the operation of the transformedposition specifying unit 233A according to the embodiments. FIG. 7 showsa diagram describing the operation of the transformed positionspecifying unit 233A in the two-dimensional OCT image. In FIG. 7 , partssimilarly configured to those in FIG. 6 are denoted by the samereference numerals, and the description thereof is omitted unless it isnecessary.

Here, the scan angle is “φ”, the scan radius is “r”, the depth range inwhich OCT measurement can be performed is “d”, the length of thetomographic image in the depth direction is “h”, and the lateral lengthof the tomographic image is “w”. The scan angle φcorresponds to thedeflection angle of the measurement light LS around the scan centerposition Cs. The scan radius r corresponds to the distance from the scancenter position Cs to a zero optical path length position where themeasurement optical path length and the reference optical path lengthare substantially equal. The depth range d is a value (known) specificto the apparatus, the value being uniquely determined by the opticaldesign of the apparatus.

The transformed position specifying unit 233A specifies the transformedposition (X, Z) in a second coordinate system from the pixel position(x, z) in a first coordinate system. The first coordinate system is acoordinate system having the origin at the upper left coordinateposition in the OCT image (B-scan image). The first coordinate system isdefined by an x coordinate axis having the B-scan direction as the xdirection and a z coordinate axis, which is orthogonal to the xcoordinate axis, having the A-scan direction as the z direction. Thepixel position (x, z) in the OCT image is defined in the firstcoordinate system. The second coordinate system is defined a Zcoordinate axis (for example, second axis) and a X coordinate axis (forexample, first axis). The Z coordinate axis has the traveling directionof the measurement light LS having the scan angle of 0 degrees withrespect to the measurement optical axis passing through a predeterminedsite (for example, fovea) in the fundus Ef, as the Z direction. The Xcoordinate axis has the B-scan direction orthogonal to the Z coordinateaxis at the predetermined site, as the X direction. In the secondcoordinate system, a predetermined Z position is set as the origin ofthe Z coordinate axis so that the position of the scan radius r becomesthe deepest portion in the measurement optical axis passing through thepredetermined site (for example, the fovea). Further, a predetermined Xposition in the measurement optical axis passing through thepredetermined site (for example, the fovea) is set as the origin of theX coordinate axis so as to have a predetermined depth direction length das described below. The transformed position (X, Z) is defined in thesecond coordinate system. The transformed position (X, Z) corresponds tothe pixel position (x, z), and is a position along the travelingdirection of the measurement light LS passing through the scan centerposition Cs (A-scan direction).

The transformed position specifying unit 233A specifies the transformedposition (X, Z) based on the scan radius r of the A-scan direction, thescan angle φ, the depth range d in which the OCT measurement can beperformed, and the pixel position (x, z). The transformed positionspecifying unit 233A can specify at least one of the X component of thetransformed position (component of the first axis direction) and the Zcomponent of the transformed position (component of the second axisdirection).

For the OCT image (tomographic image) in which the number of A-scanlines is “N” (N is a natural number), the transformed position (X, Z),which corresponds to the pixel position (x, z) in the n-th (n is anatural number) A-scan line, is specified as shown in Equations (1) and(2).

$\begin{matrix}\lbrack {{Equation}1} \rbrack &  \\{{X = {\frac{w}{2} + {( {r - d + z} ) \times {\sin( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )}}}}} & (1)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}2} \rbrack &  \\{Z = {{( {r - d + z} ) \times {\cos( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )}} - {( {r - d} ) \times \cos\frac{\varphi}{2}}}} & (2)\end{matrix}$

Here, the length “h” in the depth direction of the OCT image, the length“w” in the horizontal direction of the OCT image, and the x component ofthe pixel position are expressed by Equations (3) to (5).

$\begin{matrix}\lbrack {{Equation}3} \rbrack &  \\{h = {r - {( {r - d} ) \times \cos\frac{\varphi}{2}}}} & (3)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}4} \rbrack &  \\{w = {2r \times \sin\frac{\varphi}{2}}} & (4)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}5} \rbrack &  \\{x = n} & (5)\end{matrix}$

In Equations (1) and (2), the x coordinate of the pixel position isexpressed by Equation (5). Thus, the transformed position specifyingunit 233A can specify the transformed position (X, Z) from the pixelposition (x, z), based on the scan radius r, the scan angle φ, and thedepth range d.

In some embodiments, for the scan data, the transformed positionspecifying unit 233A can specify the transformed position (X, Z) basedon the scan radius r in the A-scan direction, the scan angle φ, thedepth range d in which the OCT measurement can be performed, and thescan position, in the same way as above.

In some embodiments, the scan radius r is specified by analyzing thedetection result of the interference light LC obtained using the OCToptical system 8. This allows to specify the transformed position (X, Z)that more accurately reflects the eyeball optical characteristics ofsubject's eye E.

In some embodiments, the transformed position specifying unit 233Aspecifies the scan angle φ by performing ray trace processing on themeasurement light LS based on the corneal shape information of thesubject's eye E. Examples of the corneal shape information include acorneal curvature radius (curvature radius of an anterior surface ofcornea, curvature radius of a posterior surface of cornea) and cornealthickness. This allows to specify the transformed position (X, Z) thatmore accurately reflects the eyeball optical characteristics ofsubject's eye E.

The transformed position specifying unit 233A can apply the abovetransformation processing of pixel positions in the two-dimensionalimage to the three-dimensional image.

FIG. 8 shows a diagram describing the operation of the transformedposition specifying unit 233A according to the embodiments. FIG. 8 showsa diagram describing the operation of the transformed positionspecifying unit 233A in the three-dimensional OCT image. In FIG. 8 ,parts similarly configured to those in FIG. 7 are denoted by the samereference numerals, and the description thereof is omitted unless it isnecessary.

In FIG. 8 , a Y plane is defined in addition to the X plane and the Zplane in FIG. 7 . In addition to the parameters shown in FIG. 7 , thecentral angle in the C-scan direction is “θ”, and the length in theC-scan direction is “lc”.

The transformed position specifying unit 233A specifies the transformedposition (X Y, Z) in a fourth coordinate system from the pixel position(x, y, z) in a third coordinate system. The third coordinate system is acoordinate system having the origin at the upper left coordinateposition in the three-dimensional OCT image. The third coordinate systemis defined by the x coordinate axis having the B-scan direction as the xdirection, a y coordinate axis, which is orthogonal to the x coordinateaxis, having the C-scan direction as the y direction, and the zcoordinate axis, which is orthogonal to both of the x coordinate axisand they coordinate axis, having the A-scan direction as the zdirection. The pixel position (x, y, z) in the OCT image is defined inthe third coordinate system. The fourth coordinate system is defined theZ coordinate axis, the X coordinate axis, and a Y coordinate axis. The Zcoordinate axis has the traveling direction of the measurement light LShaving the scan angle of 0 degrees with respect to the measurementoptical axis passing through a predetermined site (for example, fovea)in the fundus Ef, as the Z direction. The X coordinate axis has theB-scan direction orthogonal to the Z coordinate axis at thepredetermined site, as the X direction. The Y coordinate axis has theC-scan direction orthogonal to the Z coordinate axis at thepredetermined site, as the Y direction. In the fourth coordinate system,a predetermined Z position is set as the origin of the Z coordinate axisso that the position of the scan radius r becomes the deepest portion inthe measurement optical axis passing through the predetermined site (forexample, the fovea). Further, a predetermined X position and Y positionin the measurement optical axis passing through the predetermined site(for example, the fovea) are set as the origin of the X coordinate axisand the Y coordinate axis so as to have a predetermined depth directionlength d as described below. The transformed position (X, Y, Z) isdefined in the fourth coordinate system. The transformed position (X, Y,Z) corresponds to the pixel position (x, y, z), and is a position alongthe traveling direction of the measurement light LS passing through thescan center position Cs (A-scan direction).

The transformed position specifying unit 233A can specify at least oneof the X component, the Y component, or the Z component of thetransformed position.

For the OCT image (tomographic image) in which the number of A-scanlines is “N” (N is a natural number) and the number of B-scan lines is“M” (M is a natural number), the transformed position (X, Y, Z), whichcorresponds to the pixel position (x, y, z) in the n-th (n is a naturalnumber) A-scan line of the m-th (m is a natural number) B-scan line, isspecified as shown in Equations (6) to (8).

$\begin{matrix}\lbrack {{Equation}6} \rbrack &  \\{X = {\frac{w}{2} + \frac{( {r - d + z} ) \times {\tan( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )}}{\sqrt{{\tan^{2}( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )} + {\tan^{2}( {{\frac{\theta}{M} \times m} - \frac{\theta}{2}} )} + 1}}}} & (6)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}7} \rbrack &  \\{Y = {\frac{lc}{2} + \frac{( {r - d + z} ) \times {\tan( {{\frac{\theta}{M} \times m} - \frac{\theta}{2}} )}}{\sqrt{{\tan^{2}( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )} + {\tan^{2}( {{\frac{\theta}{M} \times m} - \frac{\theta}{2}} )} + 1}}}} & (7)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}8} \rbrack &  \\{Z = {\frac{( {r - d + z} )}{\sqrt{{\tan^{2}( {{\frac{\varphi}{N} \times n} - \frac{\varphi}{2}} )} + {\tan^{2}( {{\frac{\theta}{M} \times m} - \frac{\theta}{2}} )} + 1}} - ( {r - h} )}} & (8)\end{matrix}$

Here, the x component and the y component of the pixel position areexpressed by Equations (9) to (13) from the length h in the depthdirection, the length w in the B-scan direction, and the length lc inthe C-scan direction of the three-dimensional OCT image.

$\begin{matrix}\lbrack {{Equation}9} \rbrack &  \\{h = {r - {( {r - d} ) \times \cos\frac{\varphi}{2}}}} & (9)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}10} \rbrack &  \\{w = {2r \times \sin\frac{\varphi}{2}}} & (10)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}11} \rbrack &  \\{{lc} = {2r \times \sin\frac{\theta}{2}}} & (11)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}12} \rbrack &  \\{x = n} & (12)\end{matrix}$ $\begin{matrix}\lbrack {{Equation}13} \rbrack &  \\{y = m} & (13)\end{matrix}$

In Equations (6) to (8), the x coordinate and the y coordinate of thepixel position are expressed by Equations (12) and Equation (13). Thus,the transformed position specifying unit 233A can specify thetransformed position (X, Y, Z) from the pixel position (x, y, z), basedon the scan radius r, the scan angle φ, and the depth range d.

In some embodiments, for the scan data, the transformed positionspecifying unit 233A can specify the transformed position (X, Y, Z), inthe same way as above.

(Transforming Unit)

In case that the OCT image is a two-dimensional image, the transformingunit 233B transforms the pixel position (x, z) in the OCT image shown inFIG. 7 into the transformed position (X, Z) specified by the transformedposition specifying unit 233A. In some embodiments, for each of allpixel positions in the OCT image, the transformed position specifyingunit 233A specifies the transformed position and the transforming unit233B transforms the pixel position into the transformed position.

This allows to arrange the A-scan images, which are acquired byperforming A-scan, in the A-scan direction as shown in FIG. 9 .Therefore, even if the angle of view is wide, the tomographic image inwhich the shape of the predetermined site is similar to the actual shapecan be obtained.

Further, in case that the OCT is a three-dimensional image, thetransforming unit 233B can transform the pixel position (x, y, z) in theOCT image shown in FIG. 8 into the transformed position (X, Y, Z)specified by the transformed position specifying unit 233A. In someembodiments, for each of all pixel positions in the OCT image, thetransformed position specifying unit 233A specifies the transformedposition and the transforming unit 233B transforms the pixel positioninto the transformed position.

(Interpolating Unit)

The interpolating unit 233C interpolates pixels between the transformedpositions. For example, intervals between the A-scan images adjacent toeach other in which the pixel positions have been transformed into thetransformed position varies depending on the distance from the scancenter position Cs. The interpolating unit 233C interpolates pixel(s)between the A-scan images using a pixel in the A-scan images adjacent toeach other according to the depth position in the A-scan image. Asinterpolation processing on pixels performed by the interpolating unit233C, a known method such as a nearest neighbor method, a bilinearinterpolation method, or a bicubic interpolation method can be adopted.In some embodiments, the interpolating unit 233C interpolates pixelsbetween the A-scan images adjacent to each other according to thedistance from the scan center position Cs. For example, theinterpolating unit 233C interpolates pixels between the A-scan imagesadjacent to each other by changing interpolation processing methodaccording to the distance from the scan center position Cs.

In some embodiments, for the scan position in the scan data, the scandata is interpolated, in the same way as above.

(Image Deforming Unit)

The image deforming unit 234 shown in FIG. 4 deforms the fundus image bychanging the position of at least one pixel in the fundus image based onthe three-dimensional position specified by the pixel positionspecifying unit 232 or the three-dimensional position whose coordinatesare transformed by the shape correcting unit 233 to generate thethree-dimensional fundus image. That is, at least one of the pixels inthe two-dimensional fundus image is changed in the A-scan direction tobe converted into the three-dimensional image.

In some embodiments, the number of pixels Pn in the OCT data(tomographic image) and the number of pixels Pm in the fundus image aredifferent. In this case, the coordinate position (pixel position) withthe smaller number of pixels is interpolated to match the number ofcoordinate positions with the larger number of pixels. The interpolationmethod may be linear interpolation, spline interpolation, etc. Forexample, in case of Pm>Pn, after interpolating the pixels of the OCTdata to match the number of pixels in the fundus image, the imagedeforming unit 234 deforms the fundus image by changing the position ofat least one pixel in the fundus image based on the three-dimensionalposition of the fundus specified from the OCT data. For example, in caseof Pn>Pm, after interpolating the pixels of the fundus image to matchthe number of pixels in the OCT data, the image deforming unit 234deforms the fundus image by changing the position of at least one pixelin the fundus image based on the three-dimensional position of thefundus specified from the OCT data.

(Projection Unit)

The projection unit 235 projects the three-dimensional fundus imageobtained by three-dimensionalization of the fundus image onto apredetermined two-dimensional plane in the predeterminedthree-dimensional coordinate system in a line of sight direction passingthrough the point of view in the three-dimensional coordinate system.The point of view can be designated using the operation unit 240Bdescribed below. Further, the point of view can be changed by thecontroller 210 in accordance with a predetermined point of view changingalgorithm.

The controller 210 (main controller 211), as the display controller,displays the image on the display unit 240A described below, the imagebeing projected onto the two-dimensional plane by the projection unit235. For example, by moving the point of view using the operation unit240B, the orientation of the three-dimensional fundus image projectedonto the two-dimensional plane is changed. This allows to grasp themorphology of the fundus in light of its three-dimensional shape, whichhad been conventionally determined from the color of the colortwo-dimensional fundus image.

The data processor 230 that functions as above includes, for example, aprocessor described above, a RAM, a ROM, a hard disk drive, a circuitboard, and the like. In a storage device such as the hard disk drive, acomputer program for causing the processor to execute the functionsdescribed above is stored in advance.

(User Interface)

The user interface 240 includes the display unit 240A and the operationunit 240B. The display unit 240A may include the display device of thearithmetic control unit 200 and/or the display apparatus 300 describedabove. The operation unit 240B includes the aforementioned operationdevice of the arithmetic control unit 200. The operation unit 240B mayinclude various kinds of buttons and keys provided on the housing of theophthalmic apparatus 1, or provided outside the ophthalmic apparatus 1.For example, when the ophthalmic apparatus 1 has a case similar to thatof the conventional fundus camera, the operation unit 240B may include ajoy stick, an operation panel, and the like provided to the case. Inaddition, the display unit 240A may include various types of displaydevices such as a touch panel and the like provided in the housing ofthe ophthalmic apparatus 1.

It should be noted that the display unit 240A and the operation unit240B need not necessarily be formed as separate devices. For example, adevice like a touch panel, which has a display function integrated withan operation function, can be used. In such cases, the operation unit240B includes the touch panel and a computer program. The content ofoperation performed on the operation unit 240B is fed to the controller210 as an electric signal. Moreover, operations and inputs ofinformation may be performed using a graphical user interface (GUI)displayed on the display unit 240A and the operation unit 240B.

The fundus image acquired using the imaging optical system 30 is anexample of the “two-dimensional front image” according to theembodiments. The pixel position specifying unit 232 is an example of the“specifying unit” according to the embodiments. The three-dimensionalfundus image obtained by deforming the two-dimensional fundus image isan example of the “three-dimensional front image” according to theembodiments. The operation unit 240B is an example of the “designationunit” according to the embodiments. The controller 210 (main controller211) is an example of the “display controller” according to theembodiments. The imaging optical system 30 is an example of the “imagingunit” according to the embodiments. The optical system in the path fromthe interference optical system included in the OCT unit 100 to theobjective lens 22, and the image forming unit 220 (or the optical systemin the path from the interference optical system included in the OCTunit 100 to the objective lens 22, the image forming unit 220, and thedata processor 230) are an example of the “OCT unit” according to theembodiments.

[Operation]

The operation of the ophthalmic apparatus 1 according to the embodimentswill be described.

FIGS. 10 to 13 show examples of the operation of the ophthalmicapparatus 1 according to the embodiments. FIGS. 10 to 13 show flowchartsof the examples of the operation of the ophthalmic apparatus 1 accordingto the embodiments. FIG. 11 shows a flowchart of an example of theoperation of step S2 in FIG. 10 . FIG. 12 shows a flowchart of anexample of the operation of step S17 in FIG. 11 . FIG. 13 shows aflowchart of an example of the operation of step S3 in FIG. 10 . Thestorage unit 212 stores computer programs for realizing the processingshown in FIGS. 10 to 13 . The main controller 211 operates according tothe computer programs, and thereby the main controller 211 performs theprocessing shown in FIGS. 10 to 13 .

(S1: Acquire Fundus Image)

First, the main controller 211 performs alignment.

That is, the main controller 211 controls the alignment optical system50 to project the alignment indicator onto the subject's eye E. In thiscase, a fixation target generated by the LCD 39 is also projected ontothe subject's eye E. The main controller 211 controls the movementmechanism 150 based on the movement amount of the optical system torelatively to move the optical system with respect to the subject's eyeE by the movement amount. The movement amount is specified based on thereceiving light image obtained using the image sensor 35, for example.The main controller 211 repeatedly performs this processing. In someembodiments, the rough focus adjustment, the polarization adjustment,and the fine focus adjustment described above are performed after thealignment in step S1 is completed.

And then, the main controller 211 controls the imaging optical system 30to obtain the fundus image as the front image of the fundus Ef of thesubject's eye E, using the image sensor 38 (or image sensor 35). In thiscase, the main controller 211 controls the LCD 39 to display thefixation target for OCT measurement at a predetermined position on theLCD 39. The main controller 211 can display the fixation target at adisplay position on the LCD 39 corresponding to a position of an opticalaxis of the optical axis on the fundus Ef.

(S2: Acquire Tomographic Image)

Subsequently, the main controller 211 controls the OCT unit 100 and thelike to perform OCT measurement on the fundus Ef of the subject's eye E.Thereby, the OCT data and the tomographic image of the fundus Ef areacquire. The details of step S2 will be described below.

(S3: Deform Fundus Image)

Next, the main controller 211 controls the data processor 230 to deformthe fundus image acquired in step S1, using the OCT data acquired instep S2. This allows to acquire the three-dimensional front imageobtained by three-dimensionalization of the two-dimensional fundusimage. The details of step S3 will be described below.

(S4: Project)

Subsequently, the main controller 211 controls the projection unit 235to project the three-dimensional fundus image acquired in step S3 onto apredetermined two-dimensional plane in the predeterminedthree-dimensional coordinate system in a line of sight direction passingthrough the point of view. This allows to acquire an image (projectionimage) projected onto the predetermined two-dimensional plane.

(S5: Display)

The main controller 211 controls the display unit 240A to display theimage acquired in step S4. In some embodiments, the main controller 211displays at least two of the fundus image acquired in step S1, thetomographic image acquired in step S2, or the image acquired in step S4on the same screen of the display unit 240A.

This terminates the operation of the ophthalmic apparatus 1 (END).

In step S2 in FIG. 10 , processing is performed according to the flowshown in FIG. 11 .

(S11: Perform Alignment)

The main controller 211 performs alignment, in the same manner as instep S1.

In some embodiments, the processing in step S11 is omitted.

(S12: Acquire Tomographic Image for Adjustment)

The main controller 211 controls the LCD 39 to display the fixationtarget for OCT measurement at a predetermined position on the LCD 39.The main controller 211 can display the fixation target at a displayposition on the LCD 39 corresponding to a position of an optical axis ofthe optical axis on the fundus Ef.

Subsequently, the main controller 211 controls the OCT unit 100 toperform OCT provisional measurement, and to acquire a tomographic imagefor adjusting a reference position of the measurement range in the depthdirection. Specifically, the main controller 211 controls the opticalscanner 42 to deflect the measurement light LS generated based on thelight LO emitted from the light source unit 101 and to scan fundus Ef ofthe subject's eye E with the deflected measurement light LS. Thedetection result of the interference light obtained by scanning with themeasurement light LS is sent to the image forming unit 220 after beingsampled in synchronization with the clock KC. The image forming unit 220forms the tomographic image (OCT image) of the subject's eye E from theobtained interference signal.

(S13: Adjust Reference Position in Depth Direction)

Subsequently, the main controller 211 adjusts the reference position ofthe measurement range in the depth direction (z direction).

For example, the main controller 211 controls the data processor 230 tospecify a predetermined site (for example, sclera) in the tomographicimage obtained in step S12, and sets a position separated by apredetermined distance in the depth direction from the specifiedposition of the predetermined site as the reference position of themeasurement range. The main controller 211 controls at least one of theoptical path length changing units 41 and 114 according to the referenceposition. Alternatively, a predetermined position determined in advanceso that the optical path lengths of the measurement light LS and thereference light LR substantially coincide may be set as the referenceposition of the measurement range.

(S14: Adjust Focusing and Adjust Polarization)

Next, the main controller 211 performs control of adjusting focusing andof adjusting polarization.

For example, the main controller 211 controls the OCT unit 100 toperform OCT measurement, after controlling the focusing driver 43A tomove the OCT focusing lens 43 by a predetermined distance. The maincontroller 211 controls the data processor 230 to determine the focusstate of the measurement light LS based on the detection result of theinterference light acquired by the OCT measurement, as described above.When it is determined that the focus state is not appropriate based onthe determination result of the data processor 230, the main controller211 controls the focusing driver 43A again and repeats this until it isdetermined that the focus state of the measurement light LS isappropriate.

Further, for example, the main controller 211 controls the OCT unit 100to perform OCT measurement after controlling at least one of thepolarization controllers 103 and 118 to change the polarization state ofat least one of the light LO and the measurement light LS by apredetermined amount. And then, the main controller 211 controls theimage forming unit 220 to form the OCT image on the basis of theacquired detection result of the interference light. The main controller211 controls the data processor 230 to determine the image quality ofthe OCT image acquired by the OCT measurement. When it is determinedthat the polarization state is not appropriate based on thedetermination result of the data processor 230, the main controller 211controls the polarization controllers 103 and 118 again and repeats thisuntil it is determined that the polarization state of the measurementlight LS is appropriate.

(S15: Acquire Interference Signal)

Subsequently, the main controller 211 controls the OCT unit 100 toperform OCT measurement. The detection result of the interference lightacquired by the OCT measurement is sampled by the DAQ 130 and is storedas the interference signal in the storage unit 212 or the like.

(S16: Form Tomographic Image)

Next, the main controller 211 controls the image forming unit 220 toform the data set group of the A-scan image data of the subject's eye Ebased on the interference signal acquired in step S15. The image formingunit 220 forms the tomographic image by arranging the formed A-scanimages in the B-scan direction. Further, the image forming unit 220 canform a three-dimensional OCT image by arranging the tomographic images,which are arranged in the B-scan direction, in the C-scan direction.

(S17: Correct Shape)

Subsequently, the main controller 211 controls the shape correcting unit233 to correct the shape of the fundus Ef by correcting the tomographicimage formed in step S16. The main controller 211 can correct thetomographic image formed in step S16 using the eyeball parameter storedin the storage unit 212. This allows to acquire the tomographic image inwhich the A-scan images are arranged in the A-scan direction. Thedetails of step S17 will be described below.

This terminates the processing of step S2 in FIG. 10 (END).

In step S17 in FIG. 11 , processing is performed according to the flowshown in FIG. 12 .

(S21: Calculate Transformed Position)

In step S17, the main controller 211 controls the transformed positionspecifying unit 233A to specify the transformed position correspondingto the pixel position in the tomographic image formed in step S16. Thetransformed position specifying unit 233A specifies the transformedposition corresponding to the pixel position in the tomographic image,as described above.

(S22: Transform Pixel Position)

Subsequently, the main controller 211 controls the transforming unit233B to transform the pixel position in the tomographic image into thetransformed position calculated in step S21.

(S23: Next?)

The main controller 211 determine whether or not the next pixel positionshould be transformed.

When it is determined that the next pixel position should be transformed(S23: Y), the operation of the ophthalmic apparatus 1 proceeds to stepS21. When it is determined that the next pixel position should not betransformed (S23: N), the operation of the ophthalmic apparatus 1proceeds to step S24.

Through steps S21 to S23, for each pixel position of the tomographicimage, specifying the transformed position and transforming to thespecified transformed position are performed.

(S24: Perform Interpolation Processing)

When it is determined that the next pixel position should not betransformed in step S23 (S23: N), the main controller 211 controls theinterpolating unit 233C to interpolate the pixels between the A-scanimages adjacent to each other, A-scan images having been transformedinto the transformed positions in step S22.

This terminates the processing of step S17 in FIG. 11 (END).

In step S3 in FIG. 10 , processing is performed according to the flowshown in FIG. 13 .

(S31: Specify Fundus)

In step S3, the main controller 211 controls site specifying unit 231 tospecify the fundus in the tomographic image acquired in step S2.

The site specifying unit 231 specifies the fundus in the OCT data or thetomographic image formed based on the OCT data, as described above.

(S32: Specify Pixel Position)

Next, the main controller 211 controls the pixel position specifyingunit 232 to specify the three-dimensional position corresponding to eachpixel in the fundus image specified in step S31, using thecorrespondence information 212A.

(S33: Change Pixel Position)

Subsequently, the main controller 211 controls the image deforming unit234 to change the position of at least one pixels in the fundus image inthe A-scan direction, based on the three-dimensional position(s)specified in step S32.

(S34: Next Pixel?)

Next, the main controller 211 determine whether or not there is a pixelwhose pixel position should be changed next.

When it is determined that there is a pixel whose pixel position shouldbe changed next (S34: Y), the processing of the ophthalmic apparatus 1proceeds to step S32. When it is determined that there is not a pixelwhose pixel position should be changed next (S34: N), the processing ofthe of step S3 in FIG. 10 is terminated (END).

Modification Examples

In the above embodiments, the case where the two-dimensional fundusimage is converted three-dimensions after the shape of the tomographicimage acquired by performing OCT measurement is corrected has beendescribed. However, the configuration of the ophthalmic apparatusaccording to the embodiments is not limited thereto. For example, theabove shape correction can be performed after the two-dimensional fundusimage has been converted into the three-dimensional.

Hereinafter, a modification example of the embodiments will be describedfocusing on the differences from the embodiments.

The configuration of the ophthalmic apparatus according to themodification example of the embodiments is the same as that of theophthalmic apparatus 1 according to the embodiments.

FIG. 14 shows an example of the operation of the ophthalmic apparatusaccording to the modification example of the embodiments. FIG. 14 showsa flowchart of the operation example of the ophthalmic apparatusaccording to the modification example of the embodiments. The storageunit 212 stores a computer program for realizing the processing shown inFIG. 14 . The main controller 211 operates according to the computerprograms, and thereby the main controller 211 performs the processingshown in FIG. 14 .

(S41: Acquire Fundus Image)

First, the main controller 211 perform alignment, in the same manner asin step S1.

(S42: Acquire Tomographic Image)

Subsequently, the main controller 211 controls the OCT unit 100 and thelike to perform OCT measurement on the fundus Ef of the subject's eye E,in the same manner as in step S2. Thereby, the OCT data and thetomographic image of the fundus Ef are acquire. However, in step S42,the shape correction of the tomographic image is not performed.

(S43: Deform Fundus Image)

Next, the main controller 211 controls the data processor 230 to deformthe fundus image acquired in step S41, using the OCT data acquired instep S42, in the same manner as in step S3. This allows to acquire thethree-dimensional front image obtained by three-dimensionalization ofthe two-dimensional fundus image.

(S44: Correct Shape)

Next, the main controller 211 controls the shape correcting unit 233 tocorrect the shape of the fundus Ef by correcting the fundus imagedeformed in step S43, in the same manner as in step S17. The processingin step S44 is the same as that in step S17.

(S45: Project)

Subsequently, the main controller 211 controls the projection unit 235to project the three-dimensional fundus image acquired in step S44 ontoa predetermined two-dimensional plane in the predeterminedthree-dimensional coordinate system in a line of sight direction passingthrough the point of view, in the same manner as in step S4. This allowsto acquire an image (projection image) projected onto the predeterminedtwo-dimensional plane.

(S46: Display)

The main controller 211 controls the display unit 240A to display theimage acquired in step S45, in the same manner as in step S5.

This terminates the operation of the ophthalmic apparatus according tothe modification example of the embodiments (END).

In some embodiments, a program for causing a computer to execute theophthalmic information processing method described above is provided.Such a program can be stored in any computer-readable recording medium(for example, a non-transitory computer readable medium). Examples ofthe recording medium include a semiconductor memory, an optical disk, amagneto-optical disk (CD-ROM, DVD-RAM, DVD-ROM, MO, etc.), a magneticstorage medium (hard disk, floppy (registered trade mark) disk, ZIP,etc.), and the like. The computer program may be transmitted andreceived through a network such as the Internet, LAN, etc.

[Effects]

Hereinafter, the ophthalmic information processing apparatus, theophthalmic apparatus, the ophthalmic information processing method, andthe program according to the embodiments will be described.

An ophthalmic information processing apparatus (for example, anapparatus including the data processor 230) according to someembodiments includes a specifying unit (pixel position specifying unit232), and an image deforming unit (234). The specifying unit isconfigured to specify a three-dimensional position of each pixel in atwo-dimensional front image (fundus image) depicting a predeterminedsite (fundus Ef) of a subject's eye (E), based on OCT data obtained byperforming optical coherence tomography on the predetermined site. Theimage deforming unit is configured to deform the two-dimensional frontimage, by changing position of at least one pixel in the two-dimensionalfront image based on the three-dimensional position, to generate athree-dimensional front image (three-dimensional fundus image).

According to such a configuration, the three-dimensional position ofeach pixel in the two-dimensional front image is specified based on theOCT data obtained by performing OCT, and the position(s) of at least onepixel of the two-dimensional front image is/are changed based on thespecified three-dimensional position(s). Thereby, the front image of thesubject's eye can be converted into the three-dimensional image with asimple process. Therefore, the front image of the subject's eye can bestereoscopically observed with a simple process.

In the ophthalmic information processing apparatus according to someembodiments, the specifying unit includes a site specifying unit (231)configured to specify the predetermined site based on the OCT data; anda pixel position specifying unit (232) configured to specify thethree-dimensional position corresponding to a pixel of the predeterminedsite in the two-dimensional front image, based on correspondenceinformation (212A) in which positions of pixels of the two-dimensionalfront image are associated with A-scan positions in the predeterminedsite in advance.

According to such a configuration, the three-dimensional positioncorresponding to the pixel of the predetermined site in thetwo-dimensional front image is specified using the correspondenceinformation determined in advance. Thereby, the front image of thesubject's eye can be converted into three-dimensional image with asimpler process.

The ophthalmic information processing apparatus according to someembodiments further includes a shape correcting unit (233) configured tocorrect a shape of the predetermined site by correcting thethree-dimensional front image so as to follow traveling directions ofmeasurement light (LS).

According to such a configuration, the front image of the subject's eyecan be converted into three-dimensional image in a state where the shapeof the predetermined site of the subject's eye is corrected to theactual shape. This allows to grasp the morphology of the predeterminedsite in the subject's eye in more detail.

The ophthalmic information processing apparatus according to someembodiments further includes a shape correcting unit (233) configured tocorrect a shape of the predetermined site by correcting the OCT data soas to follow traveling directions of measurement light. The specifyingunit is configured to specify the three-dimensional position based ondata corrected by the shape correcting unit.

According to such a configuration, the front image of the subject's eyecan be converted into three-dimensional image in a state where the shapeof the predetermined site of the subject's eye is corrected to theactual shape. This allows to grasp the morphology of the predeterminedsite in the subject's eye in more detail.

The ophthalmic information processing apparatus according to someembodiments further includes a designation unit (operation unit 240B)used for designating a point of view in a predeterminedthree-dimensional coordinate system, a projection unit (235) configuredto project the three-dimensional front image onto a two-dimensionalplane in the three-dimensional coordinate system in a line of sightdirection passing through the point of view designated using thedesignation unit, and a display controller (controller 210, maincontroller 211) configured to display an image on a display unit (240A),the image being projected onto the two-dimensional plane by theprojection unit.

According to such a configuration, the three-dimensional front image canbe observed from any direction using the designation unit. Thereby, thefront image of the subject's eye can be stereoscopically observed indetail with a simple process.

In the ophthalmic information apparatus according to some embodiments,the predetermined site is a fundus (Ef) or vicinity of the fundus.

According to such a configuration, the front image of the fundus of thesubject's eye can be stereoscopically observed with a simple process.

An ophthalmic apparatus (1) according to some embodiments includes animaging unit (imaging optical system 30) configured to acquire thetwo-dimensional front image, an OCT unit (optical system in the pathfrom the interference optical system included in the OCT unit 100 to theobjective lens 22, and the image forming unit 220 (or optical system inthe path from the interference optical system included in the OCT unit100 to the objective lens 22, the image forming unit 220, and the dataprocessor 230)), and the ophthalmic information processing described anyone of the above.

According to such a configuration, the ophthalmic apparatus capable ofstereoscopically observing the front image of the subject's eye with asimple process can be provided.

An ophthalmic information processing method according to someembodiments include a specifying step of specifying a three-dimensionalposition of each pixel in a two-dimensional front image (fundus image)depicting a predetermined site (fundus Ef) of a subject's eye (E), basedon OCT data obtained by performing optical coherence tomography on thepredetermined site, and an image deforming step of deforming thetwo-dimensional front image, by changing position of at least one pixelin the two-dimensional front image based on the three-dimensionalposition, to generate a three-dimensional front image (three-dimensionalfundus image).

According to such a method, the three-dimensional position of each pixelin the two-dimensional front image is specified based on the OCT dataobtained by performing OCT, and the position(s) of at least one pixel ofthe two-dimensional front image is/are changed based on the specifiedthree-dimensional position(s). Thereby, the front image of the subject'seye can be converted into the three-dimensional image with a simpleprocess. Therefore, the front image of the subject's eye can bestereoscopically observed with a simple process.

In the ophthalmic information processing method according to someembodiments, the specifying step includes a site specifying step ofspecifying the predetermined site based on the OCT data; and a pixelposition specifying step of specifying the three-dimensional positioncorresponding to a pixel of the predetermined site in thetwo-dimensional front image, based on correspondence information (212A)in which positions of pixels of the two-dimensional front image areassociated with A-scan positions in the predetermined site in advance.

According to such a method, the three-dimensional position correspondingto the pixel of the predetermined site in the two-dimensional frontimage is specified using the correspondence information determined inadvance. Thereby, the front image of the subject's eye can be convertedinto three-dimensional image with a simpler process.

The ophthalmic information processing method according to someembodiments further includes a shape correcting step of correcting ashape of the predetermined site by correcting the three-dimensionalfront image so as to follow traveling directions of measurement light(LS).

According to such a method, the front image of the subject's eye can beconverted into three-dimensional image in a state where the shape of thepredetermined site of the subject's eye is corrected to the actualshape. This allows to grasp the morphology of the predetermined site inthe subject's eye in more detail.

The ophthalmic information processing method according to someembodiments further includes a shape correcting step of correcting ashape of the predetermined site by correcting the OCT data so as tofollow traveling directions of measurement light (LS). The specifyingstep is performed to specify the three-dimensional position based ondata corrected in the shape correcting step.

According to such a method, the front image of the subject's eye can beconverted into three-dimensional image in a state where the shape of thepredetermined site of the subject's eye is corrected to the actualshape. This allows to grasp the morphology of the predetermined site inthe subject's eye in more detail.

The ophthalmic information processing method according to someembodiments further includes a designation step of designating a pointof view in a predetermined three-dimensional coordinate system, aprojection step of projecting the three-dimensional front image onto atwo-dimensional plane in the three-dimensional coordinate system in aline of sight direction passing through the point of view designated inthe designation step, and a display control step of displaying an imageon a display unit (240A), the image being projected onto thetwo-dimensional plane projected in the projection step.

According to such a method, the three-dimensional front image can beobserved from any direction using the designation unit. Thereby, thefront image of the subject's eye can be stereoscopically observed indetail with a simple process.

In the ophthalmic information processing method according to someembodiments, the predetermined site is a fundus (Ef) or vicinity of thefundus.

According to such a method, the front image of the fundus of thesubject's eye can be stereoscopically observed with a simple process.

A program according to some embodiments causes a computer to executeeach step of the ophthalmic information processing method described anyone of the above.

According to such a program, the three-dimensional position of eachpixel in the two-dimensional front image is specified based on the OCTdata obtained by performing OCT, and the position(s) of at least onepixel of the two-dimensional front image is/are changed based on thespecified three-dimensional position(s). Thereby, the front image of thesubject's eye can be converted into the three-dimensional image with asimple process. Therefore the program capable of stereoscopicallyobserving the front image of the subject's eye with a simple process canbe provided.

<Others>

The above-described some embodiments or the modification examplesthereof are merely examples for carrying out the present invention.Those who intend to implement the present invention can apply anymodification, omission, addition, or the like within the scope of thegist of the present invention.

EXPLANATION OF SYMBOLS

-   1 Ophthalmic apparatus-   100 OCT unit-   200 Arithmetic control unit-   210 Controller-   211 Main controller-   212 Storage unit-   212A Correspondence information-   220 Image forming unit-   230 Data processor-   231 Site specifying unit-   232 Pixel position specifying unit-   233 Shape correcting unit-   234 Image deforming unit-   235 Projection unit-   E Subject's eye-   LS Measurement light

1. An ophthalmic information processing apparatus, comprising:processing circuitry configured as a specifying unit configured tospecify a three-dimensional position of each pixel in a two-dimensionalfront image depicting a predetermined site of a subject's eye, based onOCT data obtained by performing optical coherence tomography on thepredetermined site; and the processing circuitry is further configuredas an image deforming unit configured to deform the two-dimensionalfront image, by changing position of at least one pixel in thetwo-dimensional front image based on the three-dimensional position, togenerate a three-dimensional front image.
 2. The ophthalmic informationprocessing apparatus of claim 1, wherein the specifying unit includes: asite specifying unit configured to specify the predetermined site basedon the OCT data; and a pixel position specifying unit configured tospecify the three-dimensional position corresponding to a pixel of thepredetermined site in the two-dimensional front image, based oncorrespondence information in which positions of pixels of thetwo-dimensional front image are associated with A-scan positions in thepredetermined site in advance.
 3. The ophthalmic information processingapparatus of claim 1, wherein the processing circuitry is furtherconfigured as a shape correcting unit configured to correct a shape ofthe predetermined site by correcting the three-dimensional front imageso as to follow traveling directions of measurement light.
 4. Theophthalmic information processing apparatus of claim 1, wherein theprocessing circuitry is further configured as a shape correcting unitconfigured to correct a shape of the predetermined site by correctingthe OCT data so as to follow traveling directions of measurement light,and the specifying unit is configured to specify the three-dimensionalposition based on data corrected by the shape correcting unit.
 5. Theophthalmic information processing apparatus of claim 1, wherein theprocessing circuitry is further configured as a designation unit usedfor designating a point of view in a predetermined three-dimensionalcoordinate system; the processing circuitry is further configured as aprojection unit configured to project the three-dimensional front imageonto a two-dimensional plane in the three-dimensional coordinate systemin a line of sight direction passing through the point of viewdesignated using the designation unit; and the processing circuitry isfurther configured as a display controller configured to display animage on a display unit, the image being projected onto thetwo-dimensional plane by the projection unit.
 6. The ophthalmicinformation processing apparatus of claim 1, wherein the predeterminedsite is a fundus or vicinity of the fundus.
 7. An ophthalmic apparatus,comprising: an imaging unit including at least one lens and configuredto acquire the two-dimensional front image; an OCT unit including ascanner and configured to acquire the OCT data; and the ophthalmicinformation processing apparatus of claim
 1. 8. An ophthalmicinformation processing method, comprising: a specifying step ofspecifying a three-dimensional position of each pixel in atwo-dimensional front image depicting a predetermined site of asubject's eye, based on OCT data obtained by performing opticalcoherence tomography on the predetermined site; and an image deformingstep of deforming the two-dimensional front image, by changing positionof at least one pixel in the two-dimensional front image based on thethree-dimensional position, to generate a three-dimensional front image.9. The ophthalmic information processing method of claim 8, wherein thespecifying step includes: a site specifying step of specifying thepredetermined site based on the OCT data; and a pixel positionspecifying step of specifying the three-dimensional positioncorresponding to a pixel of the predetermined site in thetwo-dimensional front image, based on correspondence information inwhich positions of pixels of the two-dimensional front image areassociated with A-scan positions in the predetermined site in advance.10. The ophthalmic information processing method of claim 8, furthercomprising a shape correcting step of correcting a shape of thepredetermined site by correcting the three-dimensional front image so asto follow traveling directions of measurement light.
 11. The ophthalmicinformation processing method of claim 8, further comprising a shapecorrecting step of correcting a shape of the predetermined site bycorrecting the OCT data so as to follow traveling directions ofmeasurement light, wherein the specifying step is performed to specifythe three-dimensional position based on data corrected in the shapecorrecting step.
 12. The ophthalmic information processing method ofclaim 8, further comprising a designation step of designating a point ofview in a predetermined three-dimensional coordinate system; aprojection step of projecting the three-dimensional front image onto atwo-dimensional plane in the three-dimensional coordinate system in aline of sight direction passing through the point of view designated inthe designation step; and a display control step of displaying an imageon a display unit, the image being projected onto the two-dimensionalplane projected in the projection step.
 13. The ophthalmic informationprocessing method of claim 8, wherein the predetermined site is a fundusor vicinity of the fundus.
 14. (canceled)
 15. A non-transitory computerreadable recording medium storing a program of causing a computer toexecute steps of an ophthalmic information processing method comprising:a specifying step of specifying a three-dimensional position of eachpixel in a two-dimensional front image depicting a predetermined site ofa subject's eye, based on OCT data obtained by performing opticalcoherence tomography on the predetermined site; and an image deformingstep of deforming the two-dimensional front image, by changing positionof at least one pixel in the two-dimensional front image based on thethree-dimensional position, to generate a three-dimensional front image.